Fracking and air pollution

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Gas flaring

Global gas flaring crept up by 4.5 percent to around 140 billion cubic meters (bcm) in 2011, up from 134 bcm the previous year, and the first rise since 2008, preliminary data from the World Bank shows. Flaring of the gas (methane) is used to eliminate gas at mineral exploration sites, and is released via pressure relief valves to ease the strain on equipment. The increase is mostly due to the rise in shale oil exploration in North Dakota. Globally, flaring amounts to around 4.5 percent of global industrial emissions.[1]

In addition to methane, gas- and oil-suffused bedrock contains many toxic hydrocarbons, some of them volatile gases. As soon as a hole is drilled into the formations, the fugitive native gases can escape, including benzene.[2]


Various studies by academics, government, and industry have found that methane leakage can range from less than 1 percent to as much as 9 percent of the natural gas produced each year. The difference is attributed to the small amount of raw data available and variations in the way the data are interpreted.[3]

Using the small data available from the oil/gas industry so far, EPA has estimated that 2.8 percent of gas produced from a well each year leaks. Oil/gas companies and Devon Energy, in particular, have criticized EPA for relying on what they say is a small, outdated sample with data gaps.[3]

The Intersection Between Hydraulic Fracturing and Climate Change.

A 2011 study out of Cornell University found leakage of 2.2 to 3.9 percent of produced gas per well, and up to 8 percent.[3]

A 2012 NOAA study to be published in the Journal of Geophysical Research is considered the most authoritative because scientists based it on actual measurements of leakage at Colorado gas fields in 2008. That study found that about 4 percent of the 202 billion cubic feet of gas produced that year may have leaked in the Denver-Julesburg Basin. NOAA's assumptions have been challenged, most prominently by Michael Levi, director of the Program on Energy Security and Climate Change at the Council on Foreign Relations, who reworked the raw data of the NOAA study without the same assumptions and found leakage of 1.3 to 2.3 percent.[3]

In September 2012 researchers at the National Oceanic and Atmospheric Administration (NOAA) and the University of Colorado in Boulder reported preliminary results from a field study in the Uinta Basin of Utah suggesting methane leakage of up to 9% of total gas production, nearly double the cumulative loss rates estimated from industry data. The NOAA researchers collected their data in February 2012 as part of a broader analysis of air pollution in the Uinta Basin, using ground-based equipment and an aircraft to make detailed measurements of various pollutants, including methane concentrations.[4]

In July 2015 a study sponsored by the Environmental Defense Fund reported that fracking in the Barnett Shale region of Texas was releasing at least 50 percent more methane from drilling operations than the EPA has estimated.[5]

A 2016 Harvard study published in the Journal Geophysical Research Letters shows a 30% rise in methane admissions since 2002. The study hypothesizes that the U.S. could have caused the approximately 30-60% of the global growth in human-caused atmospheric methane emissions since 2002 because of a 30% increase in methane emissions across the U.S. The study does not pinpoint the source of the methane emissions but the 30% spike of U.S. methane emissions in 2002 coincides with the shale boom.[6]

Cornell professor Robert Howarth, who did earlier ground breaking research on methane emissions, told Climate Central that he was almost certain that the increase in methane was due to fracking and increased natural gas usage.

The Harvard researchers calculated emissions measurements with satellites rather than using leak estimates of oil and gas wells. This could account for why the Harvard methane estimates are higher than those figures produced by EPA based on leak estimates.[7]

2013 EDF study

In October 2013 the University of Texas, Austin, the Environmental Defense Fund, and nine major natural gas companies said that, in January 2013, the group will begin publishing raw data, collected at their drilling sites, and offer them for peer review.[3] The study, published in the Proceedings of the National Academy of Sciences (PNAS), was released in September 2013, and was based on methane emissions at 190 natural gas well production sites nationwide in 2012, including 490 wells and 27 fracking flowback operations. The sites were provided by the oil and gas companies involved in the study, many of which had equipment installed that either captured or combusted methane emissions. The study concluded total methane emissions from all phases of natural gas production to be about 2.3 million tonnes per year (an upstream emission of about 0.42%) -- about 10% lower than the 2011 EPA estimate of 2.5 million tonnes (with EDF finding much lower emissions during fracking then the EPA, but higher estimates during production). The EDF study found that emissions control equipment drastically reduced emissions during the well completion (fracking) process.[8]

According to Cornell University professor Anthony Ingraffea, the methane emissions control technology used at most of the sites included in the study (chosen by industry, which he said is a conflict of interest) are not used at most of the natural gas production sites nationwide, so EDF's study results are not representative of methane emissions at most wells. He also said the study sampled too few fracking sites for it to be statistically representative of nationwide fracking — only 27 of the more than 25,000 fracking operations that occurred in 2012.[9] Robert Howarth of Cornell said the study conflicts with non-industry sponsored NOAA studies finding much higher leakage rates at gas production sites, and at most could be seen as representative of best practices that should be employed at all sites. He added that the study reported a lot of flaring, which would increase methane emissions if it were simply vented (released).[10] MIT's Henry Jacoby said the great bulk of the problem is elsewhere, "downstream in the natural gas system," including poorly capped oil and gas wells no longer in production.[8]

Aside from the scientific disagreements, two critics of the study note that "The study had been viewed with skepticism before its release because 90 percent of the $2.3 million in funding came from nine energy companies, including Encana, Chevron and a subsidiary of ExxonMobil."[11]

Urban Methane leakage

Boston, Massachusetts area infrastructure loses two to three times more gas than state authorities say, adding to evidence of downstream operations' (including pipelines, storage terminals and power plants) role in greenhouse emissions according to a study published in January 2015 Proceedings of the National Academy of Sciences.[12] This is the first peer reviewed study that quantifies emissions of methane, a gas is roughly 86 times as potent as carbon dioxide as a driver of climate change over a period of 20 years, from natural gas operations in urban centers.[13] Many previous studies focused on methane leaks from the drilling and hydraulic fracturing wells. Less attention was given to natural gas storage and pipelines that deliver gas to homes.

The university researchers estimate the amount of Boston area methane lost over a year in the study area to be worth $90 million.[14]

Non-methane hydrocarbons

The 2012 Human and Ecological Risk Assessment study "An exploratory study of air quality near natural gas operations" found that a set of chemicals called non-methane hydrocarbons, or NMHCs, are in the air near drilling sites, even when fracking is not in progress. The researchers took weekly air samples at a site within one mile of 130 gas wells in Garfield County, Colorado, with little other industry aside from natural gas production. They detected more than 50 chemicals between July 2010 and October 2011, including 44 with reported health effects. The highest concentrations were measured after new wells were drilled, but the concentrations did not increase after the wells were fracked. Some chemicals were detected at levels high enough to potentially harm children who are exposed to them before birth. The authors say the source of the chemicals is likely a mix of the raw gas that is vented from the wells and emissions from industrial equipment used during the gas production process.[15]


Carcinogens can evaporate from frack wastewater and become air pollutants. Much of the equipment used in the drilling, production, processing, and transporting of natural gas and oil releases significant amounts of volatile organic compounds (VOCs) and nitrogen oxides (NOx), which combine in the presence of sunlight to form ground-level ozone or “smog.”[16] and particulate matter.[17]

According to the state of Colorado, natural gas and oil operations were the largest source of ozone-forming pollution, VOCs and NOx, in 2008. Elevated ozone (smog) levels near drilling sites after increased oil/gas extraction have been found in Wyoming[18][19] and Utah.[20] The Texas Commission on Environmental Quality has reported that storage tanks used in the exploration and production of natural gas and oil are the largest source of VOCs in the Barnett Shale.[21]

In 2012, diesel engine fumes were reclassified by the WHO's International Agency for Research on Cancer (IARC) from group 2A of probable carcinogens to group 1 of substances that have definite links to cancer.[22]


All of the toxins used in fracking are unknown, as oil and gas extraction facilities are not covered under the Toxics Release Inventory (TRI) program. It is known that, of the 2,500 products used in fracking, more than 650 contain known carcinogens and other hazardous substances, according to a 2011 congressional report. The EPA estimates that the oil and gas industry as a whole emits 127,000 tons of hazardous air pollutants every year, including benzene, a known carcinogen.

In October 2012, OMB Watch and 16 local, regional, and national organizations filed a petition under the TRI, calling on the EPA to require the oil and gas industry – including companies engaged in fracking – to report their toxic emissions, to provide EPA with more information on the identity, use, and quantity of chemicals used by the oil and gas industry that would help the agency evaluate their health and environmental risks. The groups claim the EPA has the authority to require the entire oil and gas extraction industry to report releases of toxic chemicals under the federal TRI program (some states have their own disclosure rules, but often with exemptions for proprietary trade secrets.)[23]

Proposed federal regulations

Air pollutants

The Environmental Protection Agency (EPA) is finalizing air pollution standards for natural-gas drilling. The standards were proposed in summer 2012 in response to complaints from citizens and environmental groups that gases escaping from the 13,000 wells drilled each year by fracking were causing health problems and widespread air pollution.[24]

The rules would require all new and any modified wells to use equipment to capture fumes that escape in the production and processing of natural gas. The fumes include methane, a potent GHG and the main component of natural gas, and volatile organic compounds, which contribute to ground-level ozone (smog). The regulations will also limit emissions from compressors, oil storage tanks and other oil-and-gas sector equipment. Complying with the mandates is projected to lower methane emissions by about 26 percent and toxic air emissions by 30 percent, according to the EPA. The rules are expected on April 17, 2012, due to a court-ordered deadline. The underlying emissions rules for gas drilling operations were last modified in 1985, and and applies only to leak detection at new and upgraded gas processing plants.[25][26]

The rules were issued on April 18, 2012, and will be fully effective in January 2015. The EPA said the new rule would reduce emissions of volatile organic compounds by 190,000 to 290,000 tons per year and toxic air pollutants by 12,000 to 20,000 tons a year, and would save the gas industry $11 million to $19 million a year because drillers would be able to capture and sell the methane that is currently being burned off, or flared.[24]

Carbon dioxide emissions

On March 27, 2012, the EPA released its new rule limiting CO2 emissions from future electricity generating plants in the U.S., which proposes that new plants emit no more than 454 kilograms of CO2 per megawatt‐hour. It would go into effect in 2013. Science concluded that the cap is unlikely to have much impact on power plants fueled by natural gas: "Nearly all gas-fired power plants built in the U.S. since 2005 would already meet the standard, according to EPA, as would typical gas plants on the drawing boards."[27]

Various reports and studies have concluded that the reduced CO2 emissions at gas plants will be negated if methane leakage during the gas production life cycle is not reduced.[28][29][30][31]



  1. Henning Gloystein and Alessandra Prentice, "Exclusive: Shale causes rise in waste gas pollution," Reuters, May 2, 2012.
  2. Sandra Steingraber, "Safe Hydrofracking Is the New Jumbo Shrimp," HuffPo, June 4, 2012.
  3. 3.0 3.1 3.2 3.3 3.4 Gayathri Vaidyanathan and Saqib Rahim, "Data-heavy project aims to move methane emissions research beyond 'he said, she said,'"] E&E, October 15, 2012.
  4. Jeff Tollefson, "Methane leaks erode green credentials of natural gas," Nature 493, 12, January 2, 2013.
  5. " "Methane from fracking is probably more of a problem than EPA thinks"] John Light, Grist, July 8, 2015.
  6. Bobby Magill, "US 'likely culprit' of global spike in methane emissions over last decade," The Guardian, February 17, 2017.
  7. Bobby Magill, "US 'likely culprit' of global spike in methane emissions over last decade," The Guardian, February 17, 2017.
  8. 8.0 8.1 Richard A. Lovett, "Study revises estimate of methane leaks from US gas fields: Leaks are minimal during removal of fracking fluids but increase once gas is flowing," Nature, September 16, 2013.
  9. Bobby Magill, "Fracking May Emit Less Methane Than Previous Estimates," Climate Central, Sep 16, 2013.
  10. "Howarth response," Cornell press release, Sep. 11, 2013.
  11. "Study Delivers Good, Bad News on Methane Leaks from Fracking Operations" Lisa Song & Jim Morris, InsideClimateNews, September 16, 2013.
  12. "Methane Leaks From Gas Pipelines Far Exceed Official Estimates, Harvard Study Finds" Lisa Song, Inside Climate News, January 28, 2015.
  13. Bobby Magill, "US 'likely culprit' of global spike in methane emissions over last decade," The Guardian, February 17, 2017.
  14. "Methane Leaks From Gas Pipelines Far Exceed Official Estimates, Harvard Study Finds" Lisa Song, Inside Climate News, January 28, 2015.
  15. Colborn T, Schultz K, Herrick L, and Kwiatkowski C. "An exploratory study of air quality near natural gas operations," Human and Ecological Risk Assessment: An International Journal November 9, 2012.
  16. "Fracking: The New Global Water Crisis," Food and Water Watch Report, March 2012.
  17. "Science And The Fracking Boom: Missing Answers," NPR, May 15, 2012.
  18. "Wyoming's natural gas boom comes with smog attached" Mead Gruver, Associated Press, March 9, 2011.
  19. "Wyoming's smog exceeds Los Angeles' due to gas drilling" USA Today, March 9, 2011.
  20. Mark Jaffe, "Like Wyoming, Utah finds high wintertime ozone pollution near oil, gas wells," The Denver Post, February 26, 2012.
  21. Elena Craft, "Do Shale Gas Activities Play A Role In Rising Ozone Levels?" Mom’s Clean Air Force, July 13, 2012.
  22. Kate Kelland, "Diesel Exhaust Fumes Cause Lung Cancer, WHO Says," Planet Ark, June 13, 2012.
  23. [ "Petition Seeks Information on Toxic Fracking Emissions,"} OMB Watch, Oct. 24, 2012.
  24. 24.0 24.1 John Broder, "U.S. Caps Emissions in Drilling for Fuel," New York Times, April 18, 2012.
  25. Andrew Restuccia, "Greens blast industry 'misinformation' on EPA 'fracking' rules," The Hill, April 9, 2012.
  26. Jennifer A. Dlouhy, "Industry asks for more time to comply with drilling pollution mandates," Fuel Fix, April , 2012.
  27. David Malakoff, "Imposing a Cap With Holes," Science, March 27, 2012.
  28. "Greater focus needed on methane leakage from natural gas infrastructure," Proceedings of the National Academy of Sciences, February 2012.
  29. Nathan Myhrvold and Ken Caldeira, "Greenhouse gases, climate change and the transition from coal to low-carbon electricity," Environmental Review Letters 7 014019, February 2012.
  30. Robert W. Howarth, Renee Santoro, and Anthony Ingraffea, "Methane and the greenhouse-gas footprint of natural gas from shale formations: A letter," Climatic Change, March 2011.
  31. "Leaking Profits: The U.S. Oil and Gas Industry Can Reduce Pollution, Conserve Resources, and Make Money by Preventing Methane Waste," NRDC, March 2012.

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