Stage 3: Exploratory Drilling

Health issues in this section:

Air Quality Water Quality Water Quantity Safety Diseases Quality of Life

What is the company doing at this stage?

While geophysical prospecting is the initial method used to evaluate potential hydrocarbon sources, the only definitive way to indicate oil and gas presence is by drilling an exploratory well. At first, one exploratory well is typically drilled on a particular pad (although a number of exploratory wells may be drilled in a geographic area to estimate the extent of the resource), but once the company hones in on the best spots for the resource, then multiple wells may be drilled on the pad during the subsequent development phase. It is important to note, however, that many exploratory wells are not successful and thus are never fully developed. The process for well construction and drilling is described below.

The operator often first works with the landowner to select a well pad site and determine the need for access roads. After upgrading local roads or constructing new ones, the operator clears and levels the land and builds the pad. Construction of a well pad can take several weeks to months, depending on the characteristics of the site, the target formation, and the company’s exploration and development approach. 1 As part of the well pad infrastructure, the operator installs facilities for storing drilling fluids and disposing of wastewater in either pits or tanks. Pipelines may also be built for the transport of water to and from the site (for more information on pipelines, see Appendix E). Companies may also construct temporary residences for their workers. In doing so, they are required to follow local and state health department regulations for housing and waste disposal. 2

Over the construction period, heavy trucks move earth and transport equipment and supplies to and from the site, including the drilling rig, storage containers, temporary worker housing, and office trailers. The amount of traffic can vary substantially depending on the activity at the site, peaking in the days before and after the drilling and completion of each well. According to one estimate, there can be a total of 1,148 one-way heavy truck trips and 831 one-way light truck trips during the early phase of well development. 3 Throughout the exploratory drilling phase, trucks will continue to provision the site with water, food, and fuel. The operator must follow the U.S. Department of Transportation’s regulations for planning and permitting the transport of heavy loads. 

At this exploratory stage, companies typically bring in experienced contract workers to work on the drilling rigs. As an example of the workforce that can be required, the consultancy IHS Energy estimates that the drilling and fracturing of a typical oil well in the Bakken Shale requires 50 full-time employees. 4 During the drilling phase, employees might work 12-hour shifts on a rig that operates 24 hours a day. At other times, the crew working on a rig might be much smaller. Some workers might be present on a site for only a matter of hours to perform a specific task, or could rotate among multiple wells on the same day. 5 

Once the equipment, infrastructure, and drilling rig are in place, the operator prepares to drill the well. A blowout prevention device is installed for safety purposes, in case a high-pressure zone is encountered. Then the operator begins drilling a hole in the earth called a wellbore. Drilling fluid, also known as drilling mud, is pumped into the wellbore to lubricate the drill and maintain the proper balance of pressure in the uncased wellbore. At selected depths in the underlying geology, the bit is removed from the wellbore and layers of steel casing and cement are installed to seal the well off from the surrounding rock, both to stabilize the wellbore and protect underground water sources (see Figure 2). Each casing is pressure-tested after the cement is installed and has set. Depending on the well location and geology of the site, the well is then drilled vertically to a median depth of 8,100 feet, 6 typically thousands of feet below groundwater resources, and gradually angled to a horizontal drilling position as it reaches the shale formation.  

Figure 2. Horizontal Well Construction

Source: The Geological Society of America.

During drilling, measurements will be taken in the well to characterize the subsurface thickness and depth of formations, the mineralogy, and the types of fluids present. Drill cuttings - rock fragments generated by the drill bit – are examined to help determine if oil and gas are present and if so, in what quantity. Models based on this combined data can help establish a reliable prediction for hydrocarbon presence on a basin-wide scale. If the resource appears promising, the operator will proceed with completing and flow testing the well, and will likely drill, complete, and flow test additional exploratory wells to evaluate a particular geographic area.

After casing the wellbore, the operator begins the completion process, preparing it to produce oil or gas by removing the drilling rig and replacing it with a workover or completion rig. The well is first tested for integrity. Then the process of hydraulic fracturing begins. To fracture the shale, the operator inserts a perforating tool into the wellbore at the depth of the shale formation, which creates holes in the well casing. This is done in stages. High volumes of fracturing fluid - a mixture typically composed predominantly of water, along with sand and chemicals – are injected into the well at high pressure so that the fluid can flow through new or existing fractures in the shale rock. The sand holds these fractures open, allowing the oil or gas to flow back towards the wellbore. During the exploration phase, the natural gas produced by the well (or co-produced, in the case of a shale oil well) might be released into the atmosphere (vented), burned off (flared), or captured and sent to market. For more information on venting and flaring, see the Air Quality section below. 

According to the American Petroleum Institute, oil and gas exploration and production generated 149 million barrels of drilling waste in 1995 (the last time an analysis was conducted), which is primarily composed of drill cuttings and mud. 7 Most of the waste is buried onsite or temporarily stored and then transported to landfills. 8 As with produced water, solid wastes may also be disposed of in Underground Injection Control (UIC) wells, which are regulated under the Safe Drinking Water Act (see Appendix C for more information on UIC wells). In some cases, the drill cuttings may be reused – for example, applied to roads for dust suppression purposes. Although such waste applications are regulated in many states, concerns have been raised about potential soil and water contamination from re-purposing the waste in this way (see Box 8). 9

After the exploratory wells are completed and flow tested, the company studies the data collected to determine whether operations in the area are financially viable, a calculation that includes production potential, the acreage under the company’s control, and the current value of the resource. A site could remain dormant for several years while the company weighs the costs and benefits and waits for the right economic conditions to materialize. The time for deliberation is limited by states, however, which require the operator to either put a well into production within a certain timeframe – which varies by state – or temporarily or permanently abandon the site.

Rig in operation (currently drilling) in WV. By Samantha Malone


  1. George Blankenship, Blankenship Consulting LLC, personal communication on August 2, 2014.
  2. For an example of state guidelines for temporary housing, see Ohio Environmental Protection Agency, Guidance for Temporary Housing Associated with Oil and Natural Gas Drilling Operations (May 2012) 
  3. New York State Department of Environmental Conservation, High-Volume Hydraulic Fracturing in NYS: 2015 Final Supplemental Generic Environmental Impact Statement (SGEIS) Documents (April 2015), 6-305.
  4. Ken Cohen, “What Does It Mean to Frack a Well? Part 1,” ExxonMobil Perspectives (June 15, 2015).
  5. George Blankenship, personal communication on August 2, 2014.
  6. Based on an EPA analysis of operator disclosures to FracFocus. Well depths ranged from 2,900 – 13,000 feet (5th to 95th percentile). U.S. Environmental Protection Agency (EPA) Office of Research and Development (ORD), “Analysis of Hydraulic Fracturing Fluid Data from the FracFocus Chemical Disclosure Registry 1.0” (Washington, DC:  U.S. EPA, March 2015), 63.
  7. U.S. Environmental Protection Agency (EPA), “Exemption of Oil and Gas Exploration and Production Wastes from Federal Hazardous Waste Regulations,” (Washington, DC:  October 2002), 2.
  8.  Ground Water Protection Council, “State Oil and Gas Regulations Designed to Protect Water Resources” (2014), 12.
  9.  Maryland Institute for Applied Environmental Health (School of Public Health, University of Maryland), “Potential Public Health Impacts of Natural Gas Development and Production in the Marcellus Shale in Western Maryland” Prepared for the Maryland Department of the Environment and the Maryland Department of Health and Mental Hygiene (July 2014), 47, 93.

What might my community experience?

With the installation of project infrastructure, drilling of a well, and the arrival of out-of-town workers, many of the impacts that communities experience due to shale development begin at this stage, although they may differ in intensity in later phases of the process. Your community might see an increase in traffic, road dust, and noise – and perhaps experience a change in the viewshed – as project infrastructure is installed. One of the most dramatic effects in many communities, particularly in small towns and rural areas, is the arrival of outside contract workers, who can bring changes to the economy, social structure, and health profile of the local community over the life cycle of the project.

Population Influx and Boom-and-Bust Effects

In extractive sector industries such as mining or conventional oil and gas development, it has long been recognized that the establishment of a project – or even the prospect of one – can lead to a population increase in local communities as non-residents move to the area for jobs and other benefits afforded by the project (a phenomenon also known as in-migration). While there are economic benefits to be gained from this population growth, depending on the profile of the community and the level of in-migration, it can strain local infrastructure, services, and government capacity to respond to changes. 

Moreover, when the project ends and benefits dwindle, the trend can be reversed as the local economy declines and people leave the area. As described under Quality of Life – Economic Impacts below, if not planned for and managed appropriately, this boom-and-bust cycle can leave the community in a worse economic situation than at the outset. Early planning to manage and mitigate population influx is essential, as is planning for the effective management of tax revenues and royalties to help communities prepare for the long term and the end of the project life cycle.

While many health issues associated with natural resource extraction in the exploration stage are related to population influx, others are tied to the presence of project infrastructure. Both types of impacts are discussed below. 

What health considerations are there?

The activities that take place during the exploratory drilling stage can introduce a range of health concerns. The project has the potential to affect the community’s air quality, water quality, safety, disease burden, and health-related quality of life (including changes to the local economy, society, noise level, and viewshed).  

What health considerations are there?

Air Quality

Shale development can introduce a broad range of local air quality concerns, some of which appear later in the development and production phases. Many of them begin with the drilling of exploratory wells and carry on through the later phases of development and production.  The major sources of potential air quality impacts include venting and flaring of natural gas from wells and fugitive emissions from oil and natural gas processing equipment; diesel-powered trucks and machinery; road dust; evaporation from storage pits; and dust from silica sand (see Box 6 on silica dust). Depending on the people affected and the exposure levels and pathways, these emissions can potentially provoke a variety of health effects, ranging from a nuisance, to acute to chronic respiratory problems, to psychological stress caused by the perception of worsened air quality. For a summary of the potential health effects of air pollutants from shale development, see Table 3.

While there are few studies of air quality in the vicinity of shale development sites, there are numerous documented community complaints of odors and other symptoms consistent with exposure to contaminants from oil and gas operations, such as upper respiratory ailments and skin irritation. 1 One Colorado study measured air samples near well pads during the well completion phase and found that volatile organic compounds (VOCs), an ozone precursor, were present more frequently and at higher concentrations than in regional ambient air samples. 2 Residents nearest to the well pads were found to be at higher risk of acute and sub-chronic respiratory, neurological, and reproductive effects. 3

In another study in the Barnett Shale region of Texas, researchers established a regional air monitoring network to monitor for VOCs near Dallas-Fort Worth, an area of high-density shale development. 4 They compared the monitoring data to a variety of regulatory health-based air comparison values (HBACVs) and found that none of the VOCs measured exceeded the HBACVs, concluding that the community was not being exposed to VOCs at a level that would cause a health concern. 5 Given that this was a community-scale study, the authors noted that individual property owners could potentially be exposed at higher or lower levels than those measured. 6

In addition to monitoring location, the variability of air emissions at shale development sites (due to the intermittent use of equipment; the varying composition of shale formations and fracturing fluids; and the influence of weather patterns and terrain, among other factors) could be responsible for differing outcomes between the Texas and Colorado studies. 7 Some researchers have concluded that further study – including community-based research – is needed in order to account for the potential cumulative impacts of the various sources of air pollution over time at shale development sites. 8, 9

Venting and flaring

Prior to the installation of equipment for collecting natural gas at an oil or gas well site, operators historically vented or flared the natural gas produced by the exploratory well. Venting has the effect of releasing methane, the primary component of natural gas – along with VOCs like benzene, toluene, ethyl benzene, and xylene (the BTEX chemicals) – directly into the atmosphere. Methane itself is principally a safety hazard if it accumulates in closed spaces; it can cause asphyxiation or explosions at high concentrations. VOCs can cause health issues such as respiratory problems and eye and skin irritation and, under certain conditions, can combine with other hydrocarbons to produce ground-level ozone, which might cause lung damage at high exposure levels. Chronic and prolonged exposure to ozone can result in asthma, lung disease, and cardiovascular effects.

As an alternative, flaring can take place in a closed incinerator box or, more commonly, at the top of a tall flare stack. The operator may also flare the gas when testing well flow or in emergency situations to prevent explosions or fires. Flares have a destruction efficiency of at least 98%, 10 thus significantly reducing methane and VOC emissions. Natural gas flaring principally forms carbon dioxide and water, but also results in some residual emissions of combustion byproducts, such as carbon monoxide and nitrogen oxides. 11 Flaring typically lasts between three and ten days and can create loud noise and heat, often requiring companies to notify local communities and fire departments before the burn takes place.

To avoid the environmental and health issues associated with venting, incinerating, or flaring the gaseous materials during a well completion, many companies now capture the marketable gas in a process referred to as a green completion. Effective January 2015, new EPA regulations under the Clean Air Act (Amendment of New Source Performance Standards 12) require 95% of VOCs from natural gas wells to be captured by green completions 13 as the well is prepared for production. Under the EPA rules, venting, incinerating, or flaring may still occur under certain circumstances; for example, during periodic maintenance and emergencies.

In August 2015, the EPA issued additional proposed rules that apply green completion requirements to shale oil wells. 14 The rules will apply only to sources newly constructed or modified after the date of proposed rule publication in the Federal Register (September 18, 2015). The agency intends to have the final rules in place in 2016. (For more information on laws and regulations, see Appendix C.)

Fugitive emissions

Local air quality might not only be impacted through operational releases of gases, but also through fugitive emissions of methane and VOCs due to leakage at wellheads, pipelines, storage tanks, compressors, and other equipment. There is uncertainty about how much leakage occurs and studies have drawn varying conclusions, depending on the method used to calculate emissions. In light of the new EPA requirements for green completions and the reduction of fugitive emissions from equipment and infrastructure, fugitive emissions from shale development should be significantly reduced. 15, 16 EPA’s August 2015 proposed rules require operators to locate and plug leaks from pneumatic pumps, pneumatic controllers, and compressor stations, among other sources.

Diesel-powered trucks and machinery

The estimated 1,148 one-way heavy truck trips during the early phase of well development 17 can result in significant emissions from diesel fuel combustion. The preparation of drilling sites and construction of rigs and other industrial infrastructure require operation of heavy machinery, which is often diesel-powered. Once well drilling operations begin, diesel-powered generators usually power the drills and power the pumps and compressors that force hydraulic fracturing fluid down wells and funnel natural gas through pipelines.

Diesel fuel contains PM2.5, or very fine particulate matter, that can penetrate deep into the lungs if inhaled. Exposure to diesel fuel exhaust and its components (such as arsenic, benzene, formaldehyde, and nickel) can cause immediate health effects such as cough, headaches, lightheadedness, and irritation of the eyes, nose, and throat. It can exacerbate respiratory illnesses, and studies have indicated that long-term exposure can lead to the increased risk of lung cancer. 18 For vulnerable populations, such as the elderly or those with respiratory conditions, exposure to high levels of fine-particle pollution is linked to increases in hospital admissions, emergency room visits, asthma attacks, and even premature deaths. 19

The many diesel-powered engines used in shale development also result in emissions of carbon monoxide (CO), nitrogen oxides (NOX), sulfur dioxide (SO2), and volatile organic compounds (VOCs). Under certain conditions, NOX and VOCs can combine to form ground-level ozone, which brings its own health concerns (see Table 3).

In 2007, EPA issued the “Highway Diesel Rule,” which set new emissions standards for heavy-duty vehicles. This new ruling is expected to reduce harmful emissions from diesel fuel by 90%. The NIEHS Working Group on Unconventional Natural Gas Drilling Operations indicated that the impact of this rule on diesel fuel emissions from shale development operations is unknown and an important subject for further study. 20

Road dust

The construction and maintenance of oil and gas operations entails the transport of heavy equipment and truck traffic on local roads. New access roads may also be constructed to accommodate this traffic. The particulate matter (PM2.5 and PM10) generated can cause respiratory effects, particularly in vulnerable individuals. Dust can also worsen visibility conditions on roads, which can lead to traffic accidents.

Evaporation pits

Large surface pits that store produced water and other wastewater from the shale development process can be a source of emissions when VOCs and other hazardous air pollutants (HAPs) volatilize from the stored water. These pits were mostly used in Western states, and their use is declining as the industry transitions to the use of storage tanks for wastewater, either on the well pad or in a central location. 


  1. Adgate, Goldstein, and McKenzie, “Potential Public Health Hazards, Exposures and Health Effects from Unconventional Natural Gas Development,” Environmental Science and Technology (2014), 8310-11.
  2. Adgate, Goldstein, and McKenzie, “Potential Public Health Hazards,” 8310.
  3. Adgate, Goldstein, and McKenzie, “Potential Public Health Hazards,” 8314.
  4. Several previous air quality studies in the Dallas-Fort Worth area indicated that VOC emissions did not exceed air quality standards and that shale development is not the largest source of emissions (motor vehicles are). See B. Zielinska, D. Campbell, V. Samburova, “Impact of Emissions from Natural Gas Production Facilities on Ambient Air Quality in the Barnett Shale Area: A Pilot Study,” Journal of the Air Waste Management Association 64 (December 2014), 1369-1383;  Rachel Rawlins, “Planning for Fracking on the Barnett Shale: Urban Air Pollution, Improving Health Based Regulation, and the Role of Local Governments,” Virginia Environmental Law Journal 31 (2013), 226-306; Charles G. Groat and Thomas W. Grimshaw, Fact-Based Regulation for Environmental Protection in Shale Development, report by the Energy Institute (University of Texas-Austin:  February 2012).The 2014 Bunch et al. study aimed to build on previous shorter-term studies.
  5. A.G. Bunch, C.S. Perry,  L. Abraham, D.S. Wikoff, J.A. Tachovsky, J.G. Hixon, J.D. Urban, M.A. Harris, L.C. Haws, “Evaluation of Impact of Shale Gas Operations in the Barnett Shale Region on Volatile Organic Compounds in Air and Potential Human Health Risks,” Science of the Total Environment 468-469 (2014), 832-833.
  6. Bunch et al., “Evaluation of Impact of Shale Gas Operations,” 841.
  7. Gregg P Macey, Ruth Breech, Mark Chernaik, Caroline Cox, Denny Larson, Deb Thomas, and David O Carpenter, “Air Concentrations of Volatile Compounds near Oil and Gas Production: A Community-Based Exploratory Study,” Environmental Health 13  (2014), 3.
  8. Charles W. Schmidt, “Blind Rush? Shale Gas Boom Proceeds Amid Human Health Questions,” Environmental Health Perspectives 119, no.8 (August 2011) 
  9. Macey et al., “Air Concentrations of Volatile Compounds,” 1.
  10. Dana R. Caulton et al., “Methane Destruction Efficiency of Natural Gas Flares Associated with Shale Formation Wells,” Environmental Science and Technology 48, no. 16 (July 30, 2014), 9548-9554.
  11. U.S. Environmental Protection Agency, “Compilation of Air Pollutant Emission Factors,” AP-42, Fifth Edition (1995), 13.5-1 -13.5-3.
  12. U.S. Environmental Protection Agency, “EPA’s Air Rules for the Oil and Natural Gas Industry: Summary of Key Changes to the New Source Performance Standards,” accessed November 21, 2014 
  13. Green completion technologies vary by basin type.
  14.  U.S. EPA, “Proposed Climate, Air Quality and Permitting Rules for the Oil and Natural Gas Industry:  Fact Sheet,” 1
  15. U.S. EPA, “Proposed Climate, Air Quality and Permitting Rules for the Oil and Natural Gas Industry: Fact Sheet,” 1.
  16. U.S. Environmental Protection Agency, EPA’s AirRules for the Oil and Natural Gas Industry: Summary of Key Changes to the New Source Performance Standards, accessed November 21, 2014
  17. New York State Department of Environmental Conservation, High-Volume Hydraulic Fracturing in NYS: 2015 Final Supplemental Generic Environmental Impact Statement (SGEIS) (April 2015), 6-305.
  18. California Office of Environmental Health Hazard Assessment, “Health Effects of Diesel Exhaust,” accessed December 6, 2014.
  19. California Office of Environmental Health Hazard Assessment, “Health Effects of Diesel Exhaust.”
  20. Penning et al., “Environmental Health Research Recommendations from the Inter-Environmental Health Sciences Core Center Working Group on Unconventional Natural Gas Drilling Operations,” Environmental Health Perspectives 122.14 (November 2009), 10.

What health considerations are there?

Table 3: Examples of Fracturing Fluid Additives and Main Compounds 1

Note: It is important to take level of exposure into account when considering health effects of pollutants.


What is it?

Health Effect


A colorless, odorless, tasteless, and flammable gas that is the primary component of natural gas.

Toxicological data suggests that pure methane is nontoxic. 2 High concentrations can cause oxygen-deficient air spaces, fire hazards, or explosions. 3 Water contaminated with methane poses risk of explosion if ignited. 4 

Hydrogen Sulfide

Chemical air hazard produced during petroleum/natural gas drilling and refining. 5 It is a colorless, flammable, and extremely hazardous gas with a strong odor of rotten eggs at low concentrations. Regulations require onsite monitoring for hydrogen sulfide. 

Lower levels and long-term exposure can cause eye irritation, headache, and fatigue. 6 Inhalation of very high concentrations can result in respiratory distress, respiratory arrest, or death. 7


A volatile organic compound (VOC) found in crude petroleum, natural gas, and diesel exhaust. May be released during well unloadings or other maintenance. 8 It is a colorless to light yellow liquid with an aromatic odor.

Low levels of exposure can result in irritation to skin, eyes, and respiratory systems, dizziness, tremors, and fatigue, among other symptoms; it has also been linked to reproductive effects. 9 Exposure to very high concentrations has been linked to leukemia and can result in death. 10


A VOC found in natural gas and hydrocarbons issuing from the well during the fracturing process. It is a colorless liquid with a sweet-smelling odor and is flammable.

Low levels of exposure are not associated with health risks. 11 However, short-term exposure at high levels can cause dizziness, confusion, irritation of skin, eyes, and throat, difficulty breathing, and possible changes in the liver or kidneys. Very high levels can result in unconsciousness or death. 12


A VOC found naturally in hydrocarbon deposits, and might be present in chemicals used during the drilling and fracking process. 13 It is a colorless liquid with distinct sweet odor.

Symptoms of low to moderate levels of toluene exposure include fatigue, confusion, memory loss, nausea, loss of appetite, and hearing and vision loss. 14, 15 Inhalation of high levels can cause light-headedness, dizziness, fatigue, unconsciousness, and death; it has also been linked to birth defects and kidney damage. 16


A VOC that is highly flammable; vapors can be explosive. 17 It is a colorless liquid with a gasoline-like odor.

Inhalation is most common route of exposure, but it can be found in contaminated private wells. 18 Inhalation of low levels is not associated with health effects. 19 High levels can result in nausea, eye and nose irritation, nerve damage, and paralysis. 20

Particulate matter (PM2.5 and PM10)

PM2.5 and PM10 are microscopic particles that can be found in diesel or smoke, near roads, or in dusty areas.

Due to their small size, these particles can be inhaled deeply into the lungs and some can enter the bloodstream, affecting the lungs and heart. 21 Individuals with heart or lung diseases, older adults, and children are particularly at risk. Short-term exposure can worsen existing lung or heart conditions. 22 Long-term exposure is linked to chronic bronchitis and premature death in some cases. 23

Ground-level ozone (smog)

Under certain conditions, ozone can be formed when VOCs react with nitrogen oxide, which is found where combustion occurs, such as in diesel engines.

Short-term exposure can cause cough, reduced lung capacity, throat irritation, and other temporary respiratory effects. 24 Evidence about the effects of long-term exposure is inconclusive, although some studies link daily exposure to elevated levels of ozone with asthma, cardiovascular effects, increased hospital admissions, and increased daily mortality. 25 Children, older adults, and people with lung disease are at greatest risk. 26



  1. Modeled on Alliance of Nurses for Healthy Environments, “Facts on Fracking: What Healthcare Providers Need to Know,accessed November 21, 2014 
  2. Seth Shonkoff, Jake Hays, and Madelon L. Finkel,  “Environmental Public Health Dimensions of Shale and Tight Gas DevelopmentEnvironmental Health Perspectives 122, Issue 8 (August 2014).
  3. Indiana Department of Natural Resources, Division of Oil and Gas, Division of Reclamation, and Indiana State Department of Health, “Methane Gas & Your Water Well: A Fact Sheet for Indiana Water Well Owners” (no date).
  4. New York State Department of Health, “A Public Health Review of High Volume Hydraulic Fracturing for Shale Gas Development” (December 2014).
  5. Occupational Safety and Health Administration (OSHA), “OSHA Fact Sheet: Hydrogen Sulfide” (2005).
  6. Agency for Toxic Substances and Disease Registry (ATSDR), Division of Toxicology and Human Health Sciences, “Hydrogen Sulfide- ToxFAQs” CAS # 7783-06-4 (October 2014).
  7. ATSDR, “Hydrogen Sulfide.”
  8. Centers for Disease Control and Prevention (CDC), “Facts about Benzene” (updated February 2013).
  9. CDC, “NIOSH Pocket Guide to Chemical Hazards” (updated February 13, 2015).
  10. CDC. “NIOSH Pocket Guide to Chemical Hazards.”
  11. ATSDR, “Xylene: Division of Toxicology and Environmental Medicine ToxFAQs” (August, 2007).
  12. ATSDR, “Xylene.”
  13. Valerie J. Brown, “Industry Issues: Putting Heat on Gas,” National Center for Biotechnology Information (February 2007).
  14. ATSDR, “Toluene: Division of Toxicology and Environmental Medicine ToxFAQs,” CAS # 108-88-3 (February 2001).
  15. Valerie J. Brown, “Industry Issues.”
  16. ATSDR, “Toulene.”
  17. ATSDR, “n-Hexane,” CAS ID # 110-54-3 (updated March 3, 2011).
  18. ATSDR, “Toxicological Profile for n-Hexane” (July 1999).
  19. ATSDR, “Toxicological Profile for n-Hexane.”
  20. ATSDR, “Toxicological Profile for n-Hexane.”
  21. U.S. EPA Office of Air and Radiation, “Particle Pollution and Your Health” (September 2003).
  22. U.S. EPA Office of Air and Radiation, “Particle Pollution and Your Health.”
  23. U.S. EPA Office of Air and Radiation, “Particle Pollution and Your Health.”
  24. U.S. EPA, “Health Effects of Ozone in the General Population” (updated January 30, 2015).
  25. U.S. EPA, “Health Effects of Ozone in the General Population.”
  26. U.S. EPA, “Ground-level Ozone:  Health Effects” last updated October 1, 2015.

What health considerations are there?


As silica sand is commonly used as a proppant during the hydraulic fracturing of shale deposits – requiring up to 10,000 tons of sand for the fracturing and re-fracturing of a single well 1  – the mining of silica sand for shale development operations has increased dramatically in recent years. Much of this silica is mined and processed in western Wisconsin, where the number of active silica sand facilities increased from 7 in 2010 to 85 in 2015. Illinois, Texas, and Minnesota also have significant silica sand facilities. 2, 3 This boom in the production of silica sand has led to concerns about increased exposures for workers and residents near sand mining and shale development operations.

What are the health concerns with silica dust?

Silica dust, officially known as respirable crystalline silica, is composed of microscopic particles about 100 times smaller than ordinary beach or playground sand. It has long been known that silica dust creates health risks for employees working in certain industries, including during the mining of this naturally occurring mineral. Health risks from exposure include respiratory problems like bronchitis and asthma; chronic obstructive pulmonary disease (COPD); silicosis, which is a permanent scarring and chronic inflammation of lung tissue; lung cancer; and kidney disease. Exposure has also been associated with some autoimmune disorders like rheumatoid arthritis and lupus, as well as with heart disease. 4  

What is workers’ exposure to silica?

In June 2012, the Occupational Safety and Health Administration (OSHA) disseminated a hazard alert for workers in the oil and gas industry, based on air samples taken at shale development sites. 5, 6 Many samples showed potential exposure levels above those considered safe, and some sites had levels ten times or more above the current permissible exposure limit (PEL). In September 2013, based on new research and analysis, the OSHA proposed more stringent standards for silica exposure. 7 If adopted, the new regulations would limit worker exposure to a PEL of 50 micrograms of respirable crystalline silica per cubic meter of air, averaged over an 8-hour workday. In addition, OSHA suggested provisions for measuring exposures and for reducing or mitigating risk. The National Industrial Sand Association (NISA), an industry group, has also developed a program for eliminating the adverse health effects of inhaled respirable silica through a program of careful monitoring and management of exposures. 8

What is the community’s exposure to silica?

The risks to communities in proximity to sand mining and shale development operations are currently not well understood. Community members near sand mining sites have voiced concerns about the local air quality and potential water contamination due to both the silica dust around the sites and the chemicals used in processing the sand. Silica dust could also affect residents living near rail lines transporting silica sand. In addition, some have pointed out that agricultural soils around mining sites may be compromised as the dust blows across farmland. 9 

To better understand the risks to communities near silica sand mines, in September 2013 the National Institutes of Health (NIH) approved a grant to the University of Iowa to study the impact of mines on respirable crystalline silica levels in nearby communities. 10 The researchers plan to take air samples from nearby homes, as well as to assess silica sand migration during rail transport.

What can be done to address health concerns?

Operators:  The OSHA-NIOSH hazard alert and the NISA program contain the following recommendations that companies should undertake to protect workers:

  • exploring the safety and effectiveness of alternative proppants

  • monitoring the air at well pads for respirable silica using the new proposed standards

  • controlling dust exposure through wetting down the sand and using air filters in both vehicles and buildings at the site

  • providing respiratory protection, training, and hazard information to workers

  • establishing medical monitoring of exposed workers 11

Groups concerned about the effects on communities have also made suggestions for improving public safety, such as installing air monitors every 1,000 feet around the perimeter of sand mining facilities and using closed-car rail transport when possible. 12

Drilling truck convoy. Courtesy of WV Host Farms Program.


  1. Zahra Hirji, “’Frac Sand’ Mining Boom: Health Hazard Feared,” Inside Climate News, November 5, 2013. 
  2. Zahra Hirji, “‘Frac Sand’ Mining Boom.”
  3. Wisconsin Department of Natural Resources, “Locations of Industrial Sand Mines and Processing Plants in Wisconsin,” last revised September 8, 2015 
  4. Centers for Disease Control and Prevention, “Workplace Safety and Health Tips: Silica” (July 2013). 
  5. Occupational Safety & Health Administration (OSHA), “OSHA-NIOSH Hazard Alert: Worker Exposure to Silica during Hydraulic Fracturing,” accessed December 6, 2014.
  6. Eric Esswein, Max Kiefer, John Snawder, and Michael Breitenstein, “Worker Exposure to Crystalline Silica During Hydraulic Fracturing,” NIOSH Science Blog (May 23, 2012).
  7. OSHA, “OSHA’s Proposed Crystalline Silica Rule: Overview” (September 2013).
  8. National Industrial Sand Association, “Occupational Health Program for Exposure to Crystalline Silica in the Industrial Sand Industry” (2011).
  9. Wisconsin League of Conservation Voters, “Frac Sand Mining,” accessed December 6, 2014.
  10. University of Iowa, Environmental Health Sciences Research Center, “Exposure Assessment and Outreach to Engage the Public on Health Issues from Frac Sand Mining,” accessed December 6, 2014 
  11. OSHA, “OSHA-NIOSH Hazard Alert: Worker Exposure to Silica.”
  12. Wayne Feyereisn, “Potential-Public-Health-Risks-of-Silica-Sand-Mining-and-Processing,” slide show, available as a PowerPoint presentation through The Sand Point Times, accessed December 7, 2014. 

What health considerations are there?

Water Quality

What chemicals are used in the hydraulic fracturing process?

Hydraulic fracturing involves pumping fracturing fluid into oil and gas wells at high pressure in order to fracture underground rock formations and release the hydrocarbons within. Fracturing fluid contains a combination of chemicals to reduce friction, prevent the growth of microorganisms, and prevent corrosion and damage to the wellbore and pipes. According to an EPA analysis of operator disclosures to FracFocus, chemical additives generally make up less than 1% by mass of the fluid; approximately 88% by mass is water. 1 The remainder of the mixture (approximately 10% by mass) consists of a proppant – usually silica sand – which is added to the fluid to hold open the fractures created in the shale formation and allow the oil or gas to flow.

The chemical components of the fracturing fluid vary, depending on the company and the characteristics of the well site. (See Table 4 for a list of common components in fracturing fluid and their uses.) The EPA analysis found that a median of 14 additive ingredients were used in fracturing fluids, ranging from 4 to 28 ingredients (5th to 95th percentile), but there were only a few ingredients that appeared in more than half the disclosures. 2 Some of the potential fracturing fluid additives are known to be toxic to mammals and harmful to human health, even at very low doses. 3 4 In order to determine risks to human health, potential exposures, and exposure pathways need to be taken into account. In light of the diversity of fracturing fluid composition, the EPA study noted the importance of considering specific company practices at the local level. 5  

The FracFocus website, a joint initiative of the Groundwater Protection Council and the Interstate Oil and Gas Compact Commission, encourages companies to disclose the chemicals used in fracturing fluid. Initially voluntary, by late 2013 companies in 14 states were required to report the chemicals used in their shale development operations on FracFocus. 6  Another 6 states imposed some level of disclosure requirements, and this area of legislation continues to evolve. The EPA analysis notes that its assessment of FracFocus disclosures was limited in part by the designation of some of fracturing fluid ingredients as confidential business information (CBI). Over 70% of the disclosures reviewed in the study contained at least one ingredient designated as CBI. 7 The operator practice of claiming some fracturing fluids as confidential information has caused some stakeholders to assert the information on FracFocus is incomplete and/or unreliable. 

Finally, some companies have developed “green” fracturing fluids that reduce the volume of water required and/or replace some of the toxic chemicals with safer ones, including eco-friendly biocides. 8, 9, 10  These green alternatives may become more widely used as the technology improves and the price drops, particularly in areas where freshwater supplies are limited. 11

What happens to the fracturing fluid after it is pumped into the well?

Once the fracturing fluid has been injected into the shale formation, some of it returns to the surface as flowback. The amount of flowback returning varies widely depending on the geologic characteristics of the formation, ranging from 30% to 70% of the original volume, 12 while the remaining portion of the injected fluid remains trapped in the shale. After it interacts with the existing water and minerals in the target formation and the wellbore, the composition of the injected fluid changes. When the flowback returns to the surface, it can contain total dissolved solids (TDS), heavy metals, volatile organic compounds (VOCs), and naturally occurring radioactive material (NORM) from the deep rock strata (See Box 8. Focus on Naturally Occurring Radioactive Material) . Most of the flowback emerges in the first two weeks after hydraulic fracturing has taken place. After that, a small amount of fluid, referred to as produced water, continues to flow from the well along with the oil or gas during production. Produced water is the naturally occurring fluid present in the target formation (see Box 7. Components of Produced Water). For the purposes of this guidebook, we will hereafter refer to both types of water flowing from the well as produced water.


Box 7. Components of Produced Water 

The water in the target geologic formation, which comes up to the surface as a component of hydraulic fracturing wastewater, can contain the following constituents:

  • total dissolved solids (TDS), which are mostly salts 
  • heavy metals, such as lead, arsenic, and chromium, which are harmful to human health even at low concentrations and can bioaccumulate in food chains
  • VOCs, including the BTEX chemicals
  • NORM, which is present in small amounts in shale and other geological formations (see Box 8. Focus on Naturally Occurring Radioactive Materials)

How is wastewater handled?

There are several options for the management and disposal of well site wastewater, which includes produced water. First, it is temporarily stored at the site, either in open pits (which may or may not have a protective liner) or tanks. The industry is increasingly moving toward the use of tanks because the risk of wastewater seeping into the groundwater is greater with open pits. Furthermore, open pits can overflow during periods of heavy rains, allowing the wastewater to enter surface waters; wastewater in the pits can also evaporate, introducing pollutants into the air. With tanks, it is easier to detect and plug any leaks. On the other hand, tanks are more likely to have catastrophic failures, leading to the release of all their contents. For this reason, tanks are often surrounded by a secondary containment. 13 Many states require secondary containments, but most have yet to set standards for tank materials, which can also be a concern. 14 For example, produced water may corrode uncoated steel over time. 

Some companies recycle the wastewater for reuse in their fracturing operations and other uses. One method of disposal is to inject the wastewater in deep underground wells, which are isolated from water sources by thousands of feet of impermeable rock. These wells are permitted under the Underground Injection Control (UIC) program, which is regulated under the Safe Drinking Water Act (SDWA). There are six categories (or classes) of UIC injection wells; the oil and gas industry uses Class II injection wells to 1) permanently dispose of wastewater or 2) reinject it at the site of a production well in order to improve the recovery of the resource (see Figure 3). This method of disposal is more common in states where the underlying geology is favorable.

The wastewater could also be transported by truck or pipeline to a municipal treatment facility that is permitted to process industrial waste and drilling wastewater, either nearby or in another state. Questions have been raised, however, as to whether municipal treatment facilities have the capacity to handle the volume and type of wastewater generated by shale operations, and some facilities have refused to accept wastewater from shale operations. 1516 The wastewater could also be processed at a private industrial treatment facility that conforms to the same or similar regulatory requirements as the public treatment plants. Finally, depending on the treatment process, the wastewater can also be recycled for use in other industrial operations, as irrigation water, or even as drinking water.  

Figure 3. Produced Water Management Options

Source: Independent Petroleum Association of America, “Induced Seismicity.”

How is wastewater containing NORM handled?

If the levels of NORM (see Box 8. Focus on Naturally Occurring Radioactive Material) in the wastewater exceed standards set by state regulations or by OSHA for exposure risks, the operator is required to take it to a facility licensed to process such waste. Companies must comply with the Resource Conservation and Recovery Act (RCRA) standards for hazardous waste. 17 If the NORM levels are lower than those standards, then the wastewater can be disposed of using the methods described above for wastewater from oil and gas operations. 

Could the water resources in my community be exposed to hazardous chemicals?

The principal pathway for the chemicals and other contaminants involved in shale development to enter local waterways is through improper management and disposal of wastewater or spills. Containment ponds, impoundments, and tanks can leak, allowing wastewater to enter surface and groundwater. Accidents involving the trucks transporting wastewater or other hazardous materials can result in spills, as can faulty equipment and human error. Additional water quality degradation may result from increased sedimentation caused by the construction of well pads and use of unpaved roads.

Determining the frequency of spills can be difficult because there is no national reporting system for oil and gas industry spills and other incidents, although state and federal regulations require reporting to states under certain circumstances. One EPA analysis of available data from 11 states from the period from 2006 to 2012 identified 457 spills at hydraulic fracturing well pad sites. 18 Low-volume spills (up to 1,000 gallons) were the most common, with relatively few high-volume spills (20,000 gallons or more). Produced water was the material most frequently spilled, usually due to human error. The incidents most often took place at storage units. The study found that the spilled material came into contact with the environment in over half the incidents, mostly with the soil, although in 33 cases the fluid reached surface or groundwater. Operators are required to have procedures and systems in place to properly manage any incidents or spills that might occur.

Some have expressed concern about another pathway for the chemicals involved in shale development to reach water resources – the possibility of fracturing fluid or other contaminants migrating into underground aquifers during the hydraulic fracturing process. The Geological Society of America notes that thus far there are possibly two such cases, and in one of them the fracturing operation was within 420 feet of the aquifer. 19 In general, fracturing activities are isolated from groundwater sources by thousands of feet of impermeable rock, 20 although wells must be drilled through usable groundwater in order to reach shale formations below. At groundwater depths, wellbores are encased in multiple thick layers of steel casing and concrete in order to prevent communication between the wellbore and water resources. Groundwater can become contaminated, however, if this protective casing and cement fails due to poor construction, and there have been instances of this occurring. 21 It is also possible that drilling the shallow section of a new well could allow for temporary communication between subsurface contaminants and groundwater resources before the well is cased.

It can be difficult to ascertain whether shale development operations have adversely affected local water supplies, largely because 1) baseline studies are not often performed and 2) many basins can naturally contain some of the hydrocarbons and metals accompanying shale development, such as methane. Nonetheless, the current scientific evidence indicates it is much more likely for leaks and spills to lead to surface water contamination than for the drilling and hydraulic fracturing of a well to cause groundwater contamination. 22

The U.S. EPA has been studying the potential impact of shale development operations on drinking water resources, and released a draft assessment summarizing existing science and new EPA research in June 2015. 23 This external review draft concludes that although there are mechanisms through which shale development could impact drinking water resources, the study team did not find evidence of widespread, systemic impacts on U.S. drinking water supplies. It notes that the failure to detect such drinking water impacts could be due to 1) the absence of impacts on a nationwide scale or 2) insufficient and/or unavailable data.

Finally, emerging technologies might help to resolve some questions around water quality. There are efforts underway to develop tracers for fracturing fluids, which could help determine the fluid’s fate in the environment. 24


  1. U.S. Environmental Protection Agency (EPA) Office of Research and Development (ORD), “Analysis of Hydraulic Fracturing Fluid Data from the FracFocus Chemical Disclosure Registry 1.0” (Washington, DC:  March 2015), 62.
  2. U.S. EPA ORD, “Analysis of Hydraulic Fracturing Fluid Data,” 63.
  3. American Chemical Society, “A new look at what’s in “fracking” fluids raises red flags” (August 13, 2014).  
  4. U.S. House of Representatives, Committee on Energy and Commerce, Minority Staff, “Chemicals Used in Hydraulic Fracturing” (April 2011), 1-2.
  5. U.S. EPA ORD, “Analysis of Hydraulic Fracturing Fluid Data,” 65-66.
  6. U.S. Department of Energy, “Secretary of Energy Advisory Board Task Force Report on FracFocus 2.0” (Washington, DC:  March 28, 2014), 9. 
  7. U.S. EPA ORD, “Analysis of Hydraulic Fracturing Fluid Data,” 63- 64.
  8. Patrick J. Kiger, “Green Fracking?  5 Technologies for Cleaner Shale Energy,” National Geographic Daily News, March 19, 2014
  9. Apache Corporation, “Greener Chemicals,” accessed October 3, 2015 
  10. Nathaniel Gronwold, “Entrepreneurs Turn to Bacteria to Fight Fracking Corrosion,” (July 3, 2014), Energywire.
  11. Kiger, “Green Fracking?”
  12. U.S. DOE, Modern Shale Gas, Development in the United States: A Primer (2009), 66. 
  13. Ground Water Protection Council (GWPC), “State Oil & Gas Regulations Designed to Protect Water Resources” (2014), 11
  14. GWPC, “State Oil and Gas Regulations,” 11.
  15. Adgate, Goldstein, and McKenzie, “Potential Public Health Hazards,”8313.
  16. Geological Society of America, “Hydraulic Fracturing,” 12.
  17. U.S. Environmental Protection Agency Office of Water, A Regulators’ Guide to the Management of Radioactive Residuals from Drinking Water Treatment Technologies (Washington, DC:  2005).
  18. The study authors note that this number is likely an under-estimate of total spills rated to shale development due to the difficulty of distinguishing them from other types of spills in the oil and gas sector and to incomplete data. The study also only took spills at well pad sites into account. U.S. Environmental Protection Agency Office of Research and Development, Review of State and Industry Spill Data: Characterization of Hydraulic Fracturing-Related Spills (Washington, DC:  May 2015), 27.
  19. Geological Society of America, “Hydraulic Fracturing,” 10.
  20. An EPA analysis of disclosures to FracFocus found a median well depth of 8,100 feet, with a range of 2,900 to 13,000 feet (5th to 95th percentile).
  21. Paleontological Research Institution, “Water: Out of the Wells,” Marcellus Shale 8 (November 2011), 10 
  22. Adgate, Goldstein, and McKenzie, “Potential Public Health Hazards,” 8312.
  23. U.S. Environmental Protection Agency Office of Research and Development, Assessment of the Potential Impacts of Hydraulic Fracturing for Oil and Gas on Drinking Water Resources: Executive Summary (External Review Draft) (Washington, DC:  June 2015), ES-6. At the time of release of this guidebook, the EPA’s draft assessment is under review by the Science Advisory Board and is market as not for citation. For this reason, other than mentioning the report’s preliminary main conclusions, we are not drawing on any further details from this report in this version of the guidebook.
  24. Dave Levitan, “Algae in Glass Cases Could Determine Fracking’s Toll,” Scientific American (March 6, 2014).

What health considerations are there?

Table 4: Fracturing fluid additives and main compounds 1

Additive Type

Main Compound(s)



hydrochloric or muriatic acid

Helps dissolve minerals and initiate cracks in the rock

Antibacterial agent


Eliminates bacteria in the water that produce corrosive byproducts


Ammonium persulfate

Allows a delayed breakdown of the fracturing gel

Clay stabilizer

Potassium chloride

Brine carrier fluid

Corrosion Inhibitor

N,n-dimethyl formamide

Prevents the corrosion of pipes


Borate salts

Maintains fluid viscosity



Lowers surface tension and allows gas to escape


Acetic acid (with NH4 and NaNO2)

Reduces fluid volume and improves proppant carrying capacity

Friction Reducer

Petroleum distillate

Minimizes friction in pipes

Gel guar gum


Helps suspend the sand in water

Iron Control

Citric Acid

Prevents precipitation of metal oxides

Oxygen Scavenger

Ammonium bisulfate

Maintains integrity of steel casing of wellbore; protects pipes from corrosion by removing oxygen from fluid

pH Adjusting Agent

Sodium or potassium carbonate

Adjusts and controls pH of fluid


Silica, sometimes ceramic particles

Holds open (props) fractures to allow fluids (oil and/or natural gas) to escape from shale

Scale Inhibitor

Ethylene glycol

Reduces scale deposits in pipe


Stoddard solvent, various aromatic hydrocarbons

Improve fluid wettability or ability to maintain contact between the fluid and the pipes



Increases the viscosity of the fracture fluids and prevents emulsions


  1. Adgate, Goldstein, and McKenzie, “Potential Public Health Hazards,” 8311.

What health considerations are there?

Box 8. Focus on Naturally Occurring Radioactive Materials (NORM)

What is NORM?

Radiation is a particular kind of energy given off by unstable atoms. Our natural surroundings — including air, water, and mineral resources — contain various amounts of radioactive material. Since these radiation-emitting elements have always been a normal part of our environment, they are called naturally occurring radioactive material, or NORM.

What is the impact of radiation on humans?

Human beings are exposed to radiation from several sources, including NORM, the sun’s rays, and medical procedures. Low-level exposure is constant and can alter molecules in the human body, but the body generally protects itself from long-term damage with routine repair mechanisms. In contrast, higher levels of exposure can lead to permanent damage and can contribute to the development of cancer and other diseases. 1

What are the recommended threshold levels for radiation exposure?

The EPA has determined that any exposure to radiation carries some risk, and, as exposure doubles, risk doubles. Routes of exposure include inhalation, ingestion, and direct (external) exposure. 2, 3 One threshold for exposure set by the EPA applies to community drinking water systems. 4, 5, 6 Household radon levels and management have also been addressed by the EPA. 7

Why is it relevant to shale development?

Shale and soil particulates at the earth’s surface contain some level of NORM, but generally not in damaging amounts. NORM can be higher, however, in buried shale deposits, especially in the Marcellus Shale of northeast Pennsylvania, with emissions of up to 20 times the amount of radioactivity found in normal background emissions at the earth’s surface. Radioactive materials can also become unusually concentrated in fluids and solids from human activity such as road building, mining, and energy development, forming what is called technologically enhanced radioactive material (TENORM). The processes of drilling and hydraulic fracturing in underground shale basins can thus introduce TENORM into the liquid and solid wastes from the site. Additionally, in the presence of high salt content, radioactive materials can form solids, which accumulate on the inside of pipes and equipment, posing a particular risk for oil and gas workers. 8

Does NORM from shale development pose a risk to nearby communities?

Several recent studies have looked into the question of how much radiation communities may be exposed to during shale exploration and development. A 2012 Wilkes University study of Pennsylvania’s Marcellus Shale basin suggested that improper management of liquid and solid wastes from well sites could potentially compromise drinking water supplies, especially those downstream from water treatment plants that receive shale development wastewater. The researchers concluded that radiation risks from both liquid and solid wastes and from radon may vary by region – and even across drilling sites within a region. 9 Another report from the University of Maryland School of Public Health reached a similar conclusion -  that more information is needed, not just about radiation levels in wastewater and solid waste from shale development sites, but also at water treatment plants and landfills that receive this waste. Ultimately, it is important to examine potentially impacted drinking water for radiation levels. 10

In early 2015, the Pennsylvania Department of Environmental Protection (DEP) released a report that assessed potential worker and public radiation exposure from shale development in the state. 11 The report concluded that there is little potential risk of radiation exposure to workers and the public from the development and production of natural gas or from the disposal and treatment of wastes, provided that the fluids are not spilled. The report therefore recommended that the state should add radium to its spill protocols; it also noted that long-term disposal protocols for TENORM waste should be reviewed.

What can be done to address health concerns? What have others done?

Landowners:  The EPA recommends that individuals with private water wells test annually for constituents of concern, in this case radionuclides and radon. If standards are exceeded, the agency suggests retesting immediately and contacting local health officials. Some local health departments may provide free water testing. The EPA also suggests being aware of nearby activities that could potentially compromise well water. 12 Some states recommend that all private wells and community drinking water supplies be tested within a five-mile radius of a well pad. 13 Routine indoor radon testing is also recommended by the EPA, and in fact is required by some states as part of real estate transactions. 14

Local officials:  One example of a community solution to protect against potentially radioactive solid waste has been to test dump trucks as they enter a landfill. Using an outdoor radiation monitor will detect any radioactivity that exceeds a set threshold above background levels.

State officials:  In 2011, the Pennsylvania DEP set a statewide model for management of wastewater from shale development, requesting that operators not send this byproduct to water treatment facilities that discharge into waterways. As a result, almost 97% of wastewater from Pennsylvania energy operations is now recycled, injected into underground receiving wells, or treated at facilities that do not discharge into waterways. 15

Operators:  Both the Wilkes University and the University of Maryland studies recommend that energy development companies and municipal road maintenance crews refrain from applying wastewater fluids to roads as a de-icing and dust control technique until further investigation can determine the safety of this practice. While the Pennsylvania DEP study found little potential for exposure from wastewater-treated roads, it still recommended further study of the issue. 


  1. United States Environmental Protection Agency, “Radiation and Health,” updated June 29, 2015,
  2. U.S. Environmental Protection Agency, “Radiation and Radioactivity,” last updated January 23, 2013,
  3. U.S. Environmental Protection Agency, “Radiation Doses in Perspective,” last updated 9/24/2013,
  4. U.S. Environmental Protection Agency, “Radionuclides in Drinking Water,” updated March 6, 2012,
  5. U.S. Environmental Protection Agency, The Radionuclides Rule, June 2001,
  6. U.S. Environmental Protection Agency, “A Regulator’s Guide to the Management of Radioactive Residuals from Drinking Water Treatment Technologies,July 2005,
  7. U.S. Environmental Protection Agency, “A Citizen’s Guide to Radon, updated August 4, 2015,
  8. Courtney Sperger, Kristin Cook, Kenneth Klemow, “Does Marcellus Shale Pose a Radioactivity Risk?” Institute for Energy and Environmental Research of Northeastern Pennsylvania Clearinghouse, August 1, 2012,
  9. Sperger et al., “Does Marcellus Shale Pose a Radioactivity Risk?”
  10. Maryland Institute for Applied Environmental Health (School of Public Health: University of Maryland), “Potential Public Health Impacts of Natural Gas Development and Production in the Marcellus Shale in Western Maryland,July 2014,
  11. Perma-Fix Environmental Services, Inc.,”Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) Study Report,” prepared for the Pennsylvania Department of Environmental Protection (January 2015),
  12. U.S. Environmental Protection Agency, “Water: Private Wells,” updated March 6, 2012,
  13. Pennsylvania State University Extension Agency, “Drinking Water,” accessed November 21, 2014,
  14. U.S. EPA, “A Citizen’s Guide to Radon,” updated August 4, 2015,
  15. The Associated Press, “Marcellus Shale Gas Drillers Recycling More Waste,” The Times-Tribune (Scranton, PA),February 17, 2012,

What health considerations are there?


Shale energy development, as an industrial operation, comes with safety risks for both workers and the local community. Occupational fatalities in the United States are high in the oil and gas industry, at seven times the rate for all U.S. industries. 1  Unlike conventional oil and gas, however, shale development often takes place in close proximity to residences, in both rural and more heavily populated areas, which can also increase the risks to the public. As previously mentioned, The Wall Street Journal reported in 2013 that approximately 15.3 million people in the United States live within one mile of a well drilled since 2000. 2

The types of incidents that can threaten the safety of workers and community residents – causing injuries and even death – include vehicular accidents, spills of wastes and chemicals, blowouts (i.e., sudden, uncontrolled releases of gases or fluids), explosions, fires, and exposure to high levels of airborne chemicals.  

Vehicular Accidents

The leading cause of worker fatalities in the oil and gas industry is traffic accidents, which pose risks to both workers and the community. Traffic accidents have been on the rise in areas where shale development is occurring, with North Dakota, Pennsylvania, and Texas reporting increased road incidents involving industry trucks. 3 For example, Bradford County, Pennsylvania witnessed a 40% increase in truck traffic over a five-year period, with a corresponding increase in accidents involving large trucks. 4 The high rate of traffic accidents for the industry is attributed in part to the condition of the trucks, but may also be due to the oil and gas industry’s exemption from the highway safety regulations that limit the length of truck drivers’ shifts. 5

Uncontrolled Releases of Gas or Fluids at the Wellhead

Another safety issue occurs when gas or fluids are unintentionally released at the wellhead, causing a blowout. These rare instances can occur in both conventional oil and gas development and shale development when high pressure zones are encountered in the wellbore or there is a failure of the well casing and cement, valves, or other mechanical equipment. For this reason, blowout prevention devices are installed early in the process of drilling a well. A report from the Energy Institute at the University of Texas at Austin noted that data regarding blowout frequency are not available for onshore oil and gas wells, but offshore wells report 1 to 10 blowouts per 10,000 wells that have not yet had blowout preventers installed. 6

For workers, blowouts at the surface can create exposure risks, through inhalation of hydrocarbons and contact with chemicals. These unplanned releases can also on rare occasions lead to explosions and fires on the well pad, which endanger both workers and possibly nearby residents. 

Blowouts may also occur on the subsurface, which is harder to track, and may affect aquifers or water wells in the area. The University of Texas report cited two examples from conventional oil and gas development in Louisiana and Ohio in which underground pressure changes during drilling caused water wells in the vicinity to bubble or spout water. 7

Gas Migration into Residential Water Wells and Homes

Residents living in proximity to shale wells have also expressed concern about the possibility of toxic gases accumulating inside their water wells and homes, with inhalation risks and the potential for explosions. In most cases, such reported incidents have been attributed to naturally occurring methane migration that is unrelated to any shale energy development in the vicinity. 8

A few methane explosions in homes or well houses located near shale gas operations have been reported in Colorado, Pennsylvania, and Texas, with investigators concluding that gas may have migrated from hydraulically fractured wells nearby. In almost all such cases, gas migration occurred because well integrity was compromised due to faulty casings and/or inadequate cementing of the casings. 9

Hydrogen Sulfide

When drilling for oil and gas, workers run the risk of encountering hydrogen sulfide (or sour gas), a flammable, highly toxic gas with the odor of rotten eggs, although the odor becomes unnoticeable after a period of exposure. Although not common at conventional and shale development sites, hydrogen sulfide is toxic even at low concentrations; workers therefore wear meters to monitor for its presence. Low-level chronic exposure to hydrogen sulfide may also cause cumulative health risks for workers, as well as for nearby residents who can live many years in proximity to oil and gas facilities. 10


Most safety incidents are caused by the following:

  • an influx of trucks on local roads and unsafe driving behaviors, sometimes on the part of local drivers; inadequate driver training; drug use and fatigue while driving; and poorly maintained trucks 11
  • improper construction of wells or wastewater impoundments
  • faulty equipment, often due to inadequate maintenance
  • inadequately trained well pad personnel
  • failure to follow recommended  practices to prevent blowouts and spills
  • over-pressurized gas
  • weather, particularly extreme weather events

For options for addressing these safety concerns, see the “What Can Be Done?” section below


  1. OSHA, “Oil and Gas Extraction: Safety and Health Topics,” accessed December 1, 2014. The federal Occupational Safety and Health Administration (OSHA) is the regulatory agency for workforce safety.  The OSHA website houses a tool for the oil and gas industry that details potential health and safety hazards by stage of production, along with preventative measures and solutions for each (accessed November 22, 2014).
  2. Gold and McGinty, “Energy Boom.”
  3. Mike Lee, “In North Dakota’s Oil Patch, Wrecks Increase as Trucks Push onto Farm Roads,” E&E News, April 11, 2014; Resources for the Future, “Shale Gas Development Linked to Traffic Accidents in Pennsylvania,” March 2014; “In Texas, Traffic Deaths Climb amid Fracking Boom,” National Public Radio, October 2014.
  4. Adgate, Goldstein, and McKenzie, “Potential Public Health Hazards,” 8311.
  5. Ian Urbina, “Deadliest Danger Isn’t at the Rig but on the Road,” The New York Times (May 14, 2012)
  6.  Charles G. Groat and Thomas W. Grimshaw, Fact-Based Regulation for Environmental Protection in Shale Gas Development, Energy Institute (Austin: The University of Texas at Austin, February 2012), 22 
  7. Groat and Grimshaw, Fact-Based Regulation, 23
  8.  Groat and Grimshaw, Fact-Based Regulation, 23
  9. Groat and Grimshaw, Fact-Based Regulation. 23-24
  10. Earthworks Action, “Hydrogen Sulfide.” 
  11. Ian Urbina, “Deadliest Danger Isn’t at the Rig but on the Road,” The New York Times (May 14, 2012) 

What health considerations are there?


Mobile labor forces can contribute to disease transmission within a community, whether they consist of long-haul truckers, migrant farm workers, military personnel, or, in this case, industry workers assigned to shale development sites during the exploratory drilling and development phases. 1

In North America, the main reported communicable disease risk for communities undergoing shale gas development 2 appears to be an increase in the incidence of sexually transmitted diseases – notably chlamydia, gonorrhea, and syphilis – introduced by project workers as they pursue sexual contacts with local partners (see the Social Impacts section). In Pennsylvania’s Marcellus Shale, for example, one study found that the average increase in the occurrence of chlamydia and gonorrhea cases was 62% greater in counties experiencing shale development over those that were not. 3  In another example, syphilis rates began rising in Alberta, Canada along with tar sands development in the province. 4

There is some debate about whether adverse impacts such as an increase in the disease burden or increased crime levels are proportionate to the increase in population or are due to the particular characteristics of the temporary workforce. It is nonetheless evident that such increases, whether absolute or proportionate, can place a health burden on local health care infrastructure and resources, particularly in smaller communities. 5 


  1. Yorghos Apostolopoulos and Sevil Sonmez (eds.), Population Mobility and Infectious Disease (New York: 2007).
  2. In other parts of the world, shale gas development may pose more of a disease risk for industry workers, where the rate of endemic disease is high, both vector-borne and through person-to-person transmission — e.g., illnesses like HIV/AIDS, tuberculosis, malaria, and cholera.  Food and drinking water contamination may also pose risks for itinerant workers in some regions.  In North America, particularly in the northeast, there can be exposure to Lyme disease through tick bites, and the industry should caution workers to wear protective clothing in certain areas.
  3. Food and Water Watch, “The Social Costs of Fracking:  A Pennsylvania Case Study” (September 24, 2013).
  4. Josh Wingrove, “Alberta’s Rate of Syphilis Infection Still Rising,” The Globe and Mail, last modified August 23, 2012.
  5. Ron Dutton and George Blankenship, “Socioeconomic Effects of Natural Gas Development” (Denver, Colorado:  August 2010), paper prepared to support NTC Consultants under contract with the New York State Energy Research and Development Authority, 23.

What health considerations are there?

Quality of Life – Economic Impacts

Many communities have the opportunity to benefit from natural resource development in their area. Shale energy development offers the prospect of jobs to local economies; lease payments and royalties for property owners; and increased tax revenues, royalties, and lease payments for state and local governments. Local workers employed on shale gas projects can enhance their skills and increase their earnings potential. Projects can also stimulate demand for local businesses, including the construction, retail, and services industries. The presence of the oil and gas industry can also contribute to or attract investments in regional infrastructure, which benefits other area businesses. Such benefits can improve the economic outlook for the community and its residents, contributing to an enhanced quality of life.

Whether a community will benefit in the long term depends on several factors, principally on its size, the diversity of its economy, and the state of its economy when development begins. Smaller, rural communities with little economic diversity and a high rate of energy development activities are at greater risk of succumbing to a boom/bust cycle. 1 Larger communities can often better absorb some of the adverse effects of development. The rate of development also matters, with a slower pace allowing the community to adapt to changes, as does the extent to which benefits are accrued and spent locally. 2

One important factor in a community’s long-term economic success is whether its economy becomes dependent upon the oil and gas industry. A study of the costs and benefits of fossil fuel extraction in the western United States showed that the counties that were more dependent on extractive industries (energy focusing) did not fare as well economically in the long term as their counterparts focused on other industries. 3 

A 2014 Duke University report reviewed the fiscal impacts of shale development on local governments in the top producing counties in eight states between 2007 and 2012. 4 It found that county and municipal governments have generally received net financial benefits from shale development in the recent boom, although there has been some regional variation. Notably, costs have thus far outweighed benefits for many local governments in rural areas where large-scale development has occurred rapidly (i.e., in the Bakken Shale region of North Dakota and Montana). 


The oil and gas industry can generate three types of employment – direct employment in the activities of well construction, drilling, development, and production or related industry services; indirect employment with suppliers or service industries stimulated by industry demand; or induced employment in jobs created by oil and gas employees spending their income on goods and services. 5 In the oil and gas industry, many of the jobs generated are initial construction jobs, with fewer long-term jobs available in the production phase. It is these long term positions, however, which are considered more important to the area’s long-term economic development. 6

In the exploratory drilling phase, many of the jobs do not require specialized skills (e.g., construction, truck driving) and the operator may hire locally for such positions. Given that the initial activity is limited to one or a few wells, the impact on the local economy is relatively modest at this stage. Work on the drilling rigs does require specialized skills and the operator tends to bring in outside workers to fill these positions. Locals may be hired into retail and service industries that are responding to the increased demand from the industry and new workers. 


A limited number of outside transient workers are moving to the area at this stage, and they tend to seek temporary housing in the community or in other towns within commuting distance. If there is a housing shortage in the area, companies sometimes build temporary housing for their crews on the pad site or in another location. Often referred to as man camps, these temporary housing facilities can be the locus of some social problems (see the Quality of Life – Social Impacts section below).   

Local Infrastructure and Services

Given that outside project workers are not too numerous at this point, they usually have a limited impact on local services, principally affecting law enforcement, emergency response, and road maintenance services. 7 The transport of equipment, supplies, water, and wastes to and from the drilling site can impact the quality of roads, bridges, and the local transportation network. Road maintenance and repair is the leading cost for most county governments in areas of oil and gas development. 8 

To handle oversight, permitting, and code enforcement for the new facilities and infrastructure installed for the project, local governments might need additional resources and staffing. State and local governments can collect revenues from shale development from a variety of sources, including property taxes, lease and royalty payments on publicly owned land, and fees for services. Some states impose severance taxes 9 on operators to offset costs, and some local governments institute fees in order to fund infrastructure maintenance. Additional sales taxes can be a main source of revenue for municipal governments as the population increases with development. Local governments might also receive in-kind donations from operators who help to maintain and repair local roads, perhaps by establishing road use agreements with them.

As mentioned above, the Duke University report observed that these revenues have tended to keep pace with or exceed costs associated with shale development for most local governments. In some areas, however, additional revenues might not be commensurate with the increased demand for services. Governments also might receive these revenues later than community needs accumulate, however, leading to a funding gap. 10 This gap might begin to materialize in the exploration phase, but could become more pronounced in the development phase when there can be heavy demands on local infrastructure and services.

Quality of Life – Social Impacts

Depending on the size and existing character of the host community, an influx of temporary workers can bring increased social problems. These workers are often male and generally live in cluster housing, geographically separated from family members. They have disposable income and leisure time with which to seek entertainment or distractions. These circumstances may contribute not only to substance misuse, but also to other problems like traffic accidents, disorderly conduct, violent behavior, unwanted pregnancies, domestic violence, child abuse, and sexually transmitted diseases. Furthermore, there is evidence that illegal drug and gun trafficking, gambling, and prostitution can increase in the surrounding area. 11

As mentioned in the diseases section, it is unclear whether the increase in such social problems is proportionate to the population increase or is linked to the specific profile of the transient workers in the oil and gas industry. In any case, depending on the size and resources of the community involved, some communities can find their law enforcement, health care, and emergency response systems overwhelmed by this spike in demand. 12

Such issues may begin to emerge during the exploration phase and significantly increase during the development phase. Over time, however, as the industry matures to the production phase, the number of transient workers declines and more permanent workers fill the long-term development and production positions.

Quality of Life – Noise Impacts

Overview of the Effects of Noise

Excessive noise is not merely an annoyance, but also a health concern. Elevated noise levels can affect both hearing and speech comprehension, and can impact other physical and mental functions. The U.S. Environmental Protection Agency (EPA) has recommended outdoor limits for noise at 55 A-weighted decibels (dB [A]), and indoor limits at 45 dB (A). The agency has also noted that a 24-hour exposure above 70 dB (A) may lead to permanent hearing impairment. 13

Prolonged exposure to elevated noise levels is associated with a range of health problems. It can activate the sympathetic and endocrine systems and contribute to cardiovascular disease, prenatal complications, and immunosuppression, as well as increased incidence of diabetes, mental disorders like anxiety, and general physical and mental fatigue. These health issues can occur even when people have become habituated to the noise and claim to no longer be disturbed by it. 14

One significant impact of noise is sleep disturbance. Uninterrupted sleep is a prerequisite for physical and mental health and well-being. For a good night’s sleep, sound levels should not exceed 30 dB (A), which corresponds with average nighttime noise levels of 25 to 30 dB (A) in quiet rural and suburban areas. 15, 16 Maintaining a quiet ambiance is important because even when individuals are not awakened by it, noise can cause detectable changes in heart and brain activity, as well as in next-day stress levels. 17

Smaller increases in the normal ambient sound levels can also be a stressor. Increases of only 6 dB (A) above ambient levels can be detected by the average person. 18, 19 Exposure to this level of noise can lead to complaints of annoyance, headache, and mental and physical fatigue. The effects can vary greatly, however, depending on individual sensitivities and circumstances. With prolonged irritating noise, people may experience feelings of aggression and declines in cognition and performance. 20

Noise and Shale Development Operations

With shale development operations often taking place around-the-clock – often in otherwise quiet rural areas, where nighttime sounds can be as low as 25 to 30 dB (A) – communities are frequently concerned about the noise from these operations. According to a study of a shale development site in West Virginia, noise from diesel-powered equipment and machinery such as drills, pumps, and compressors averaged 70 dB (A) at the periphery of the site. Noises above 55 dB (A) – the level at which sound begins to become a nuisance, according to WHO 21 – occurred frequently, with occasional short bursts of noise above 85 dB (A). 22

Once drilling and hydraulic fracturing begin, the level of ambient noise can increase by 37 to 42 dB (A). 23 Well pad sites are noisiest during the phases of road and pad construction; drilling and hydraulic fracturing; and well completion. This entire process can extend intermittently over several weeks to months for the first well. When water for hydraulic fracturing is not piped to the site or recycled, large numbers of truck trips are required – up to 1,148 one-way heavy truck trips and 831 one-way light truck trips in the early phase of well development, according to one estimate. 24  A study in Colorado found that water haulage trucks emit 88 dB (A) at 50 feet and 68 dB (A) at 500 feet. 25, 26

Activities that can generate noise during the exploratory drilling phase and beyond include:

  • the construction of access roads and well pads, requiring earth-moving equipment and gravel deliveries
  • multiple truck trips to and from the site 27 
  • the drilling and hydraulic fracturing of each well, which often proceed 24 hours a day 28   
  • venting or flaring during well completion, both of which can occur around the clock for several days 29

There are a number of measures that can be taken to reduce or avoid the impacts of noise from shale development projects. These are described in the “What Can Be Done?” section below.

Quality of Life – Visual Impacts

Much shale development takes place in rural areas, with their mix of natural landscape, forests, agricultural vistas, and small communities. For communities reliant on sectors such as agriculture, tourism, and recreation, the installation of industrial infrastructure can negatively impact natural and visual resources. Surveys indicate that residents and visitors in these regions are concerned about the potential for development to diminish aesthetics, property values, tourism, and public enjoyment. 30 From a health perspective, whether in a rural or another setting, residents can experience distress as changes to their environment materialize, contributing to anxiety, depression, or anger. 31 

With shale development, multiple wells are often located on a single pad; according to industry estimates, for instance, over 90% of shale gas wells in the Marcellus Shale region will be located on multi-well pads. 32 This impacts a larger area per site compared to single-well pads, although fewer well pads overall are distributed throughout an area and require fewer access roads. Infrastructure that could have visual impacts includes the well pad site itself, fluid retention basins, access roads, and utility corridors (electric service, water pipelines, and gas-gathering pipelines). Off-site storage facilities and centralized water impoundments (often covering up to 5 acres), as well as increased population density and accompanying traffic can also cause changes to the viewshed. In addition, compressor stations, which remain in place throughout the productive life of the wells, are generally installed every 50 to 100 miles. 33, 34

As with noise, the greatest visual impacts occur during the exploratory drilling and development phases, due to the disruption of the landscape and installation of the well pad and its associated infrastructure. Although estimates vary, overall site disturbance during this phase averages 7.4 acres for a multi-well pad, and 4.8 acres for a single well pad (both estimates include portions of access roads and utility corridors). 35 The well pad alone averages 3.5 acres of disturbed land during the drilling and fracturing phase for a multi-well pad, although this can vary significantly. For example, in the Fayetteville Shale region, multi-well pad disturbance ranges from 1.7 acres to 5.7 acres. 36

Access roads add to site disturbance and may also have the requisite utility corridors running alongside. The roads are often 20 to 40 feet wide and average 400 feet in length (again, there is variation – they have been permitted for up to 3,000 feet in the Marcellus shale region 37). The installation of roads and utility corridors generally creates a linear visual disturbance in the landscape and may cause the fragmentation of wildlife habitat.

In addition to the infrastructure, numerous tanks, trucks, diesel-powered equipment, personnel sheds, and rigs for drilling (up to 100 or more feet high) and fracturing (up to 150 feet high) can contribute to the visual footprint of the site. 38 Depending on topography and any screening methods employed, daytime visual impacts are greatest up to a half mile away. Furthermore, work can take place around the clock during active well development. The lights used at night for safety purposes can disturb residents close to the site and generate an ambient sky glow. If flaring is conducted, the open flame can also be seen at a distance. 39 

PA Gas Well. Photo by Sara Gillooly, Tyler Rubright, Samantha Malone

Quality of Life – Psychological Impacts

In addition to these physical changes in a community after shale energy development begins, shifts in quality-of-life perceptions can also occur, depending on the character of the community. In smaller communities with a strong sense of community character, residents may describe no longer having a sense of peace, psychological refuge, or a rural quality of life. 40 These feelings do not necessarily correlate with actual damage or direct health impacts, but can nonetheless create stress that sometimes leads to physical illness. 41 Such feelings can become much more acute with the accelerated and cumulative changes in the development phase. Reactions to the changes brought by development can vary, however. In economically depressed areas, some residents may welcome newcomers and a sense of revitalization that development brings to their area. 42


  1. David Kay, “The Economic Impact of Marcellus Shale Gas Drilling:  What Have We Learned?  What Are the Limitations?” Working Paper Series:  A Comprehensive Economic Impact Analysis of Natural Gas Extraction in the Marcellus Shale (Cornell University: April 2011)
  2. Susan Christopherson and Ned Rightor, “How Should We Think About the Economic Consequences of Shale Gas Drilling?” Working Paper Series: A Comprehensive Economic Impact Analysis of Natural Gas Extraction in the Marcellus Shale (Cornell University: May 2011)
  3. Headwaters Economics, “Fossil Fuel Extraction as a County Economic Development Strategy:  Are Energy-focusing Counties Benefiting?” (September 2008).
  4. Daniel Raimi and Richard G. Newell, “Shale Public Finance:  Local Government Revenues and Costs Associated with Oil and Gas Development,” Duke University Energy Initiative Report (Durham, NC:  May 2014).
  5. Dutton and Blankenship, “Socioeconomic Effects,” 11.
  6. Amanda L. Weinstein and Mark D. Partridge, The Economic Value of Shale Natural Gas in Ohio (The Ohio State University Department of Agricultural, Environmental and Development Economics, December 2011),  2 
  7. Dutton and Blankenship, “Socioeconomic Effects,” 41-43.
  8. Daniel Raimi and Richard G. Newell, “Shale Public Finance,” 2.
  9. Taxes levied on the extraction of natural resources from the earth.
  10. Headwaters Economics, “Oil and Natural Gas Fiscal Best Practices: Lessons for State and Local Governments” (November 2012), 1-3.
  11. National Public Radio, “The Great Plains Oil Rush” (2014), radio broadcast.
  12. Food and Water Watch, “The Social Costs.”
  13. U.S. Environmental Protection Agency, “EPA Identifies Noise Levels Affecting Health and Welfare,” updated May 20, 2015.
  14. Monica S. Hammer, Tracy K. Swinburn, and Richard L. Neitzel, “Environmental Noise Pollution in the United States:  Developing an Effective Public Health Response,” Environmental Health Perspectives 122:  115-119.
  15. World Health Organization Europe, “Night Noise Guidelines for Europe,” (Copenhagen, Denmark: WHO Regional Office for Europe, 2009), 108.
  16. Earthworks.  Oil and Gas at Your Door? I-45.
  17. Monica S. Hammer, Tracy K. Swinburn, and Richard L. Neitzel, “Environmental Noise Pollution.”
  18. New York State Department of Environmental Conservation Study (April 2015).
  19. For a useful illustration of noise pollution from oil and gas development, a Colorado study recorded the average decibel levels of typical noises emanating from well pads (see chart Earthworks, Oil and Gas at Your Door?, pp. I-45)
  20. Hammer et al., “Environmental Noise Pollution.”
  21. Earthworks, “Oil and Gas at Your Door?” I-45.
  22. See Michael McCawley, Air, Noise, and Light Monitoring Results for Assessing Environmental Impacts of Horizontal Gas Well Drilling Operations, study for the West Virginia Department of Environmental Protection (May 3, 2013) 
  23. New York State Department of Environmental Conservation, High-Volume Hydraulic Fracturing in NYS: 2015 Final Supplemental Generic Environmental Impact Statement (SGEIS) Documents (April 2015), 6-301.
  24. New York State Department of Environmental Conservation, High-Volume Hydraulic Fracturing in NYS, 6-305.
  25. Earthworks, Oil and Gas at Your Door? 
  26. For a chart of truck noise as a function of truck size and speed, see New York State Department of Environmental Conservation Study (April 2015), 6-299.
  27. Composite noise levels for these activities can be found in New York State Department of Environmental Conservation (April 2015), 6-292 – 6-93.
  28. For composite noise levels for drilling and hydraulic fracturing, see New York State Department of Environmental Conservation Study (April 2015): pp. 6-295 – 6-297. 
  29. New EPA regulations, effective January 2015, ban venting and significantly restrict flaring.
  30. Tompkins County Council of Governments, “Community Impact Assessment: High-Volume Hydraulic Fracturing” (December 2011) 62-63.
  31. S. L. Perry, “Using Ethnography to Monitor the Community Health Implications of Onshore Unconventional Oil and Gas Developments: Examples from Pennsylvania’s Marcellus Shale,” New Solutions 23 (2013).
  32. New York Department of Environmental Conservation, Final SGEIS (2015), 5-2. 
  33. Energy Information Administration, Office of Oil and Gas, “Natural Gas Compressor Stations on the Interstate Pipeline”(November 2007).
  34. For photographs depicting visual impacts of shale gas development at various stages and from varying distances, see  Upadhyay, “Visual Impacts  of Natural Gas Drilling in the Marcellus Shale Region,” Cornell University Study (2010). For charts summarizing “Generic Visual Impacts Resulting from Horizontal Drilling and Hydraulic Fracturing in the Marcellus and Utica Shale Area of New York,” see New York State Department of Environmental Conservation Study (April 2015), 6-285 – 6-288.
  35. New York Department of Environmental Conservation, Final SGEIS (2015), 5-2.
  36. New York Department of Environmental Conservation, Final SGEIS (2015), 5-7.
  37. New York Department of Environmental Conservation, Final SGEIS (2015), 5-3. 
  38. New York Department of Environmental Conservation, Final SGEIS (2015), 6-273.
  39. As noted above, however, EPA regulations effective January 2015 restrict this practice.
  40. S. L. Perry, “Using Ethnography to Monitor the Community Health Implications of Onshore Unconventional Oil and Gas Developments: Examples from Pennsylvania’s Marcellus Shale,” New Solutions 23 (2013), 40.
  41. S. L. Perry, “Using Ethnography.”
  42. Dutton and Blankenship, “Socioeconomic Effects,” 42.

What can be done to address health concerns? What have others done?

It is important for local governments, industry representatives, and other local stakeholders to begin sharing information and opening a dialogue early in the development process. As discussed above, the long-term health of the community and its environment can be linked to the presence of industry. To ensure that the community benefits in the long term, it is important for local officials to carefully manage the short-term benefits to offset costs and prepare for the long term.

Collaborative Activities

In the exploratory drilling phase, it is still uncertain whether or not the project will proceed to development and production. Factors that enter into a company’s decision to develop the resources in the area include: the size and viability of the resource; the political and regulatory environment; the availability of local infrastructure, gathering systems, and pipelines; proximity to market; the feasibility of constructing well pads and infrastructure on the available land; presence of other operators; and oil and gas prices, which can be volatile. 1

While conversations will necessarily be iterative as circumstances change and new information emerges, it can be useful for local officials and industry representatives to hold initial discussions on the following topics:

  • information-sharing on the company’s activities and plans, to the extent possible
  • regional infrastructure development, transportation planning, traffic management, and road safety
  • approaches for meeting housing needs and maintaining the availability of affordable housing
  • educational and job-skills training programs with community leaders and local educational institutions
  • ideas for potential investment strategies to maximize project benefits and diversify and stabilize the local economy if the site moves to the development phase (recognizing that this may not occur)


  1. API “Community Engagement Guidelines,” 3

What can be done to address health concerns? What have others done?

Collaborative Activities


When a company begins exploration activities in the area, it could engage with local officials on the capacity of the local health care system and its emergency response services. Given that the operator relies on these services for the care of its personnel, it would be valuable for local health officials, company representatives, health care providers, and emergency responders to jointly identify needs. If the local health care system lacks the necessary capacity to respond to shale development-related incidents, companies could support local efforts to expand services, upgrade equipment, or provide training. 1  


  1. Daniel Raimi and Richard G. Newell, “Shale Public Finance,” 4.

What can be done to address health concerns? What have others done?

Collaborative Activities


Given that the increased occurrence of sexually transmitted diseases is common in communities with a mobile workforce, local health officials and companies could work together on informing workers, industry subcontractors, and community members about the risks and methods of prevention. It is critical for companies to provide preventative guidance and set standards for both their workers and subcontractors. 1

Sexually transmitted diseases are best prevented with the use of condoms, which should be made readily available to workers at their places of residence and in public locations like pharmacies, bars, and convenience stores. Health officials and companies could also collaborate to ensure that workers and residents have access to clinics for testing and treatment. 


  1. Shira M Goldenberg, Jean A Shoveller, Aleck C Ostry, Mieke Koehoorn, “Sexually Transmitted Infection (STI) Testing among Young Oil and Gas Workers: The Need for Innovative Place-based Approaches to STI Control,” Canadian Journal of Public Health 99, no. 4 (July/August 2008),

What can be done to address health concerns? What have others done?

Collaborative Activities

Quality of Life – Economic Impacts

In some areas, local governments, educational institutions, and companies have collaborated on designing and delivering educational and job skills training programs to equip local residents with the knowledge and skills needed to work in the oil and gas industry (see Box 10. Examples of Education and Training Programs).

Local Infrastructure & Services: To maintain local roads and infrastructure, companies and local governments can develop road use agreements that set forth parameters for the industry such as hours of usage, route selection, and upgrades. Given that much of the truck traffic to a shale development site is for the transport of water and other liquids (over 90%, according to one study 1), exploring alternatives to trucking, such as pipelines and onsite waste treatment and disposal, could be worth considering. For an overview of the issues related to pipelines, see Appendix E.


  1. New York State Department of Environmental Conservation, Final SGEIS (April 2015), 7-134.

What can be done to address health concerns? What have others done?

Local Officials and Community Leaders

Water Quality

Given that many of the potential contaminants associated with shale development, such as methane, are naturally occurring, it can be difficult to substantiate the source of any groundwater contamination. It is therefore important to establish a baseline for water quality prior to development and create an ongoing water monitoring program. Community members could have a role in assisting with water monitoring efforts. For examples of community involvement in water monitoring, see Box 4. Case Study from the Mining Industry:  Good Neighbor Agreement and the report from the International Council on Mining and Metals, Water Management in Mining.” 

What can be done to address health concerns? What have others done?

Industry Representatives

The activities described below can be undertaken by operators to address some of the air quality, water quality, safety, and quality of life concerns that are associated with exploratory drilling and subsequent phases. Some operators may already be implementing some of these options.

What can be done to address health concerns? What have others done?

Industry Representatives

Air Quality

There are a range of measures that can be taken to reduce air pollution from shale development. The EPA’s Natural Gas STAR program, a voluntary program that partners with industry, offers an extensive list of recommended technologies and practices for reducing methane and VOC emissions.

Options for reducing air emissions include:

  • transitioning from diesel-powered equipment to natural gas- or solar-powered or reduced-emission engines and motors (some companies are using gas produced at the site to fuel equipment engines, thus reducing the use of diesel fuel)
  • constructing pads and roads of gravel, or applying water or other dust suppressants to them
  • instituting carpooling and busing programs to transport workers, thereby reducing the number of vehicles accessing the site (see Box 4. Case Study from the Mining Industry:  The Good Neighbor Agreement)
  • establishing driver training and incentive programs to ensure local speed limits are obeyed (also relevant to safety; see Box 9. Case Study: Driver Safety)
  • establishing a community-based participatory monitoring program, in which trained and experienced volunteers conduct air sampling in the surrounding area to monitor for chemical constituents that could pose a health risk

In order to ascertain the amount of air emissions that might be coming from the site, it is important to conduct monitoring activities before, during, and after drilling takes place. 

What can be done to address health concerns? What have others done?

Industry Representatives

Water Quality

Approaches the operator may undertake to address water quality concerns include:

  • using tanks to store wastewater instead of open pits, following best practices for their design, construction, and operation to prevent leaks and spills 1
  • following best practices for well-casing construction, following best practices and industry guidelines 2
  • adopting the use of green fracturing fluids (strategies include drawing on the chemicals listed in EPA’s Design for the Environment program and establishing a staff position responsible for reducing the volume and toxicity of chemicals used)
  • implementing storm water plans to control runoff and flooding
  • publicly disclosing the contents of hydraulic fracturing fluids, possibly using a “systems approach” to reporting that separates trade names from chemical ingredients and concentrations, allowing operators to preserve confidential information while sharing the chemicals used 3
  • as mentioned in the safety section, providing driver training programs and establishing safety controls such as speed monitors and road risk maps to avoid accidents and spills (see Box 9. Case Study: Driver Safety)
  • establishing a community-based participatory monitoring program, in which trained and experienced volunteers conduct water sampling in the surrounding area to monitor for chemical constituents that could pose a health risk (see Box 4. Case Study from the Mining Industry:  The Good Neighbor Agreement)


  1.  GWPC, “State Oil and Gas Regulations,” 11
  2.  API, “Hydraulic Fracturing Operations – Well Construction and Integrity Guidelines,” API Guidance Document HF1, First Edition (October 2009)
  3. U.S. Department of Energy, “Secretary of Energy Advisory Board Task Force Report on FracFocus 2.0” (Washington, DC:  March 28, 2014), 2.

What can be done to address health concerns? What have others done?



Activities that can serve to protect the safety of project workers and the community include:

  • siting well pads as far away from residences and water wells as possible
  • pressure testing of blowout prevention equipment prior to production
  • following best practices and industry guidance for well construction and maintenance, particularly for well casing
  • providing safety training for workers on proper equipment maintenance and practices to prevent blowouts and spills
  • engaging in emergency planning in which operators meet with emergency room staff and local first responders to review emergency response plans and provide the information on the chemicals used at the project site
  • conducting joint trainings and drills for hazardous materials (hazmat) incidents with operators, emergency room departments, fire departments, and other first responders
  • assessing local health care and emergency response capacity and helping to improve capacity where needed
  • providing driver training programs, along with safety controls such as speed monitors, road risk maps, driver drug testing, stringent rules regarding shift lengths and proper rest, and routine vehicle maintenance and inspection 1 (see Box 9. Case Study:  Driver Safety)


  1. Ian Urbina, “Deadliest Danger Isn’t at the Rig but on the Road,” The New York Times (May 14, 2012)

What can be done to address health concerns? What have others done?

Industry Representatives

Quality of Life – Noise

The impact of noise on nearby residents can be reduced in several ways – by increasing the distance between the source of the sound and person hearing it (the receptor); by directing the noise away from the receptor; and by altering the time of day that the sound is produced. 1 It is important for the operator to be aware of the noise levels generated in order to help take appropriate corrective actions when needed; installing sound meters on the well pad to monitor sound levels 24 hours a day can therefore be useful. Residents can also monitor sound levels in their homes. 

When considering how to best mitigate noise impacts, it is important to take into account:

  • the combined effects of various sources of noise
  • the time of day when people are exposed
  • vulnerable groups, including people with medical problems or disabilities such as blindness or hearing impairment; those managing complex cognitive tasks; those in learning environments; fetuses; children, particularly during the stage of language acquisition; and the elderly
  • low frequency sounds, which are often experienced as vibrations or pressure sensitivity, and are extremely bothersome to certain individuals 2
  • distinctive sounds or those generated by an impact, particularly when they are intermittent or unpredictable
  • effects of noise on wildlife and livestock, which can also affect livelihoods

Measures that operators can undertake to reduce noise impacts in the exploratory drilling and development phases include:

  • erecting sound barriers like those used on highways around the site, or arranging infrastructure like storage tanks and other onsite materials (trucks, hay bales, topsoil) to serve as sound barriers
  • using rubber hammer covers
  • installing high-grade noise reduction baffles on equipment and air-relief lines

Quality of Life – Visual Impacts

During the construction of well pad facilities, following some basic principles may help to reduce the potential visual impacts of the site:

  • reducing the height of facilities and equipment when possible
  • placing equipment so that it is screened from view by topographical features or vegetation
  • painting equipment to blend with the surroundings
  • avoiding the use of reflective surfaces
  • ensuring the site is clean and well-kept

With regard to the potential disturbance caused by nighttime work, lighting should be used for safety purposes only and turned off when not in use. Operators can also use energy-efficient lighting and shielded light fixtures, as well as angle light paths downward rather than horizontally (see Box 11. Case Study:  West Texas Dark Sky Reserve). Nearby residents may need to use window coverings at night so that the light from the well pad does not disturb sleep or affect melatonin production and circadian rhythms. 3


  1. See New York State Department of Environmental Conservation Study (April 2015)
  2. Earthworks. Oil and Gas at Your Door?
  3. McCawley, Air Noise and Light Monitoring.

What resources can provide further information?

Exploratory Drilling Stage

  • American Petroleum Institute (API), “Hydraulic Fracturing Operations – Well Construction and Integrity Guidelines,” API Guidance Document HF1, First Edition (October 2009), API, an industry association, has produced industry guidance documents and recommended practices on shale development operations. This documents pertains to well construction, while two sets of recommended practices released in August and October 2015 address well integrity and environmental considerations:  “Hydraulic Fracturing – Well Integrity and Fracture Containment” (ANSI/API Recommended Practice 100-1) and “Managing Environmental Aspects Associated with Exploration and Production Operations Including Hydraulic Fracturing” (ANSI/API Recommended Practice 100-2). These newly released documents are available for free public viewing (or for sale to download) on the API website: To access, register, select “Browse read-only documents now,” then select “Exploration and Production,” and scroll to recommended practices 100-1 and 100-2.
  • Explore Shale, a project of Penn State Public Broadcasting funded by the Colcom Foundation, is a public media project dedicated to informing the public about hydraulic fracturing in the Marcellus Shale. The interactive media web page can be used to explore the drilling and development of the Marcellus Shale:
  • The FracTracker Alliance ( provides maps for oil and gas sites in over 30 states.  The information provided includes drilled wells, violations, proximity to populations, sand mining operations, and more.
  • Grand Valley Citizens’ Alliance, The Rifle, Silt, New Castle Community Development Plan:  A Collaborative Planning Document between the RSNC Defined Area Residents, Antero Resources Corp. and Galaxy Energy (January 1, 2006), This community development plan, developed in collaboration between the community and the industry, is a non-legally binding framework for the development of energy resources in Garfield County, Colorado. It contains ten guidelines for development, including ideas for addressing financial and infrastructure impacts to the community. It also includes provisions for community participation in the plan implementation and for community education on natural gas development operations. The agreement was challenged in 2009 when one of the companies planned to undertake more intensive development than had been agreed upon, but in the end the original planning document was upheld; see a case study of the plan at
  • The Intermountain Oil and Gas BMP Project, a project of the University of Colorado Law School, houses a database of best management practices, policies, and laws relating to oil and gas development: The database is searchable by keyword and other fields and contains best management practices on air quality, community, human health and safety, noise, visual aesthetics, water quality, and water quantity, among other issues.
  • Richard Liroff, Danielle Fugere, Lucia von Reusner, and Steven Heim, “2014 Disclosing the Facts:  Transparency and Risk in Hydraulic Fracturing,” This project of a coalition of investment advisory firms and advocacy organizations (As You Sow, Boston Common Asset Management, LLC, Green Century Capital Management, Inc. and the Investor Environmental Health Network) tracks the self-reported best practices of companies engaged in hydraulic fracturing operations in terms of environmental and community impacts. It assesses companies on their practices and disclosures in five areas: 1) toxic chemicals; 2) water and waste management; 3) air emissions; 4) community impacts; and 5) management accountability. The 2014 report is the third in a series of annual reports ranking company performance. It also highlights examples of innovative best practices.
  • Rational Middle Energy Series, Realities of Drilling:  Extended and Recut (Updated 2014), video (14:02), This video episode gives an overview of the process of drilling and hydraulically fracturing a shale well, as well as the risks involved and potential mitigation strategies.

What resources can provide further information?

Air Quality

  • The Center for Dirt & Gravel Road Studies is a non-profit organization that operates under the Larson Transportation Institute at Penn State University. The organization has several research, education, and outreach programs related to environmentally sensitive maintenance of unpaved roads and trails. Their mission is to create more environmentally friendly maintenance techniques and implement them in Pennsylvania. Their website provides:
  • Department of Health and Human Services, CDC, NIOSH, and IMA-NA, “Dust Control Handbook for Industrial Minerals Mining and Processing (January 2012). This handbook was produced for industrial minerals producers to provide guidance on use of state-of-the-art dust control techniques for all stages of mineral processing, in effort to eliminate or reduce hazardous dust exposures and create safer, healthier conditions for mine workers.
  • National Industrial Sand Association (NISA), “Occupational Health Program for Exposure to Crystalline Silica in the Industrial Sand Industry” (2011). NISA offers guidelines for industry to monitor and manage workers’ exposure to silica dust, which can occur during sand mining operations, during transport, and at the well pad.
  • Southwest Pennsylvania Environmental Health Project (SWPA-EHP), “Air.” SWPA-EHP, a nonprofit environmental health organization that provides assistance to local residents concerned about the health impacts of shale gas development, offers information and resources to residents for home air monitoring.
  • U.S. EPA, “Natural Gas STAR Program,” last updated October 23, 2014. The Natural Gas STAR Program is a voluntary program for oil and gas companies that aims to help companies employ new techniques to increase efficiency and reduce emissions. Through the Natural Gas STAR program, industry participants share information on cost-effective emission reduction technologies and practices. There is also a “Recommended Technologies and Practices“ page (last updated May 30, 2014). 

What resources can provide further information?

Water Quality

  • Agency for Toxic Substances and Disease Registry, “Toxic Substances Portal,” last updated July 23, 2014, This agency housed with the Centers for Disease Control and Prevention has a set of fact sheets on hazardous chemicals containing information on their health effects, exposure pathways, government recommendations, and ways to reduce risks.
  • Alliance of Nurses for Healthy Environments, “Assessment Tools & More,” The Alliance of Nurses for Healthy Environments (ANHE) is an international network of nurses that deals with environmental health issues through education, research, advocacy, and practice. The ANHE website contains assessment tools for healthcare practitioners in areas experiencing shale development.
  • The FracFocus website ( is a repository where operators can voluntarily disclose the chemicals used in hydraulic fracturing operations. It is searchable by well site.
  • International Council on Mining & Metals, “Water Management in Mining:  A Selection of Case Studies” (May 2012),  This selection of case studies gives some examples from the mining sector of strategies to reduce water use and protect water quality in collaboration with stakeholders.
  • Matthew McFeeley, “State Hydraulic Fracturing Disclosure Rules and Enforcement: A Comparison” (Natural Resources Defense Council, July 2012), This report discusses the importance of disclosure of the chemicals used in the shale development process to allow for water quality testing prior to exploration, and summarizes regulations by state. 
  • Southwest Pennsylvania Environmental Health Project (SWPA-EHP), “Water,” SWPA-EHP, a nonprofit environmental health organization that provides assistance to local residents concerned about the health impacts of shale gas development, offers guidance and resources on home water testing.
  • Susquehanna River Basin Commission, “Overview of Remote Water Quality Monitoring Network,” last updated June 2014, The Susquehanna River Basin Commission created the Remote Water Quality Monitoring Network to collect and analyze water quality data from the Susquehanna River. The data is used to monitor the effects of drilling operations in the area on the health of the river. 
  • Town of Palisade and City of Grand Junction, Colorado et al., Watershed Plan for the Town of Palisade and the City of Grand Junction, Colorado (August 2007), This collaboratively developed watershed plan between community, government, and company stakeholders offers a framework for identifying and addressing risks, conducting third-party water monitoring, and implementing best management practices with regard to energy development in the watershed.
  • U.S. Environmental Protection Agency Office of Research and Development, “Assessment of the Potential Impacts of Hydraulic Fracturing for Oil and Gas on Drinking Water Resources” External Review Draft (Washington, DC:  June 2015). This draft assessment provides a review and synthesis of available information concerning the potential impacts of hydraulic fracturing for oil and gas on drinking water resources in the United States. At the time of the release of this guidebook, the draft assessment is under review by the EPA’s Science Advisory Board.  

What resources can provide further information?


  • National Institute for Occupational Safety and Health (NIOSH), “NIOSH Pocket Guide to Chemical Hazards,” last updated August 5, 2013, The pocket guide contains general industrial hygiene information on chemicals for workers and occupational health professionals. It is available for download and free copies can be ordered from the website.
  • Occupational Safety and Health Administration (OSHA), “Oil and Gas Extraction,” This website has health and safety standards pertaining to the oil and gas industry. There is also a tool that details potential health and safety hazards by stage of production, along with preventative measures and solutions for each:

What resources can provide further information?

Quality of Life – Economic impacts

Quality of Life – Noise impacts

  • Earthworks, “Oil and Gas at Your Door? A Landowner’s Guide to Oil and Gas Development” (Durango, Colorado:  Oil and Gas Accountability Project, 2005) The effects of noise are covered on pp. I-45 – I-49. For a useful illustration of noise impacts  from oil and gas development, a Colorado study recorded the average decibel levels of typical noises emanating from well pads; see chart, p. I-45.
  • New York State Department of Environmental Conservation, “High-Volume Hydraulic Fracturing in NYS: 2015 Final Supplemental Generic Environmental Impact Statement Documents”   (Albany, New York:  April 2015), New York’s Final SGEIS covers a wide variety of potential issues resulting from shale gas development. For composite noise levels for drilling and hydraulic fracturing, see pp. 6-295 to 6-297. For composite noise levels of other well pad activities, see pp. 6-292 and 6-293. For a chart of truck noise as a function of truck size and speed, see p. 6-299.
  • The Noise Pollution Clearing House ( is a national non-profit organization with extensive noise-related resources. Its mission is to raise awareness about noise pollution, strengthen laws, and assist activists in order to “create more civil cities and more natural and rural wilderness areas by reducing noise pollution at the source.” To aid in their efforts, they maintain a database for noise regulations and ordinances in cities, counties, and towns within the United States:
  • The Southwest Pennsylvania Environmental Health Project, a nonprofit environmental health organization that provides assistance to local residents concerned about the health impacts of shale gas development, has guidance for monitoring noise levels in homes using smartphone apps: .

Quality of Life – Visual Impacts

Continue to Stage Four: Development & Production ➤