Fact Sheet on Air Pollution from Flares

Facts about Revised EPA Emissions Factors for Flares

Flares are used to burn off gas at drilling sites and petrochemical plants for a variety of reasons.  Sometimes the gas doesn’t meet specifications, or has to be diverted from processing units that have shut down for repairs.  Drillers may struggle for weeks or months to contain the large volume of gas or other liquids that erupt from shale formations when they are first penetrated.

Flare gas emissions are almost never monitored, but are instead estimated based on assumptions about the volume of gas sent to the flare, its chemical composition, and how well combustion destroys pollutants.

EPA estimates there are about five hundred flares at more than 100 U.S. refineries, but there are many more at chemical plants and at drilling sites.  For example, the number of flaring permits in Texas alone rose from just over a hundred in 2008 to 2,000 in 2012.  States like North Dakota now flare up to a third of their total gas production.[i]

The “emission factors” for flares developed by EPA and used by industry since at least 1991 were based on data from a “pilot test” dating back to the early 1980’s.  The Agency is required by Section 130 of the Clean Air Act to review the accuracy of those emission factors every three years, but had never done so.[ii]  Meanwhile, several remote sensing studies measuring air pollutant concentrations in the air above petrochemical plants made clear that these sources were releasing more pollution than disclosed through industry reports.

The Environmental Integrity Project filed a Data Quality Act petition on behalf of the City of Houston in 2008, asking EPA to take a second look at the Agency’s methodology for estimating emissions from flares and other sources.  After five years with no corrections from EPA, EIP filed a suit on behalf of several gulf coast environmental groups representing communities downwind from these sources, asking EPA to at least review and revise emissions factors for flares, tanks, and wastewater treatment plants. [iii]   Remote sensing studies at several refineries (including BP Texas City and Shell Deer Park in Houston) showed that all three of these sources release a lot more pollution than industry was reporting to state and federal regulators using EPA approved emission factors or similar methods for estimating emissions.[iv]

EPA Revised Estimate of Flare Emissions

After EIP filed suit to compel this review (more than 25 years after it was supposed to happen) the Agency proposed changes to emission factors for flares in August of 2014.  The revisions adopted today for flares are based on EPA’s review of actual emissions measured at the flare tip using infrared technology that measures the concentration of various pollutants based on their ability to absorb light of varying wave lengths.

  • In brief, EPA found that flares release four times the amount of smog forming volatile organic compounds than estimated under the old methodology. These “VOCs” form smog, contribute to respiratory ailments, and include carcinogens like benzene.
  • EPA unexpectedly carved out applicability of the VOC emission factors to flares at refineries and chemical plants. Historically, the emission factors for flares have been applied broadly across many different industrial sites, including oil and gas facilities. EPA’s revised factors leave a large gap in how emissions will be reported from the nation’s fast growing oil and gas sector.
  • EPA has attempted to clarify that the emission factors are only applicable to flares achieving 98% destruction efficiency. Unfortunately, EPA’s revised emission factor infers that compliance with the existing general provisions for flares ensures 98% destruction efficiency. EPA has already recognized that these requirements are not sufficient to assure 98% destruction efficiency and proposed additional requirements for refinery flares in 2014.
  • Industries that continue to use EPA emission factors (or alternatives based on EPA methods) will need to report the higher emission levels. Facilities will also continue to have the option to continuously monitor the concentration of VOCs in the gas and determine its combustibility or sample with sufficient frequency to estimate and report releases of VOCs. Alternatively, operators also have the option to conduct their own testing using available technology to develop emission factors that are representative of conditions at their flares.

What do the new emission factors mean?

  • Flare emissions are much higher than expected. For example, VOC emissions from refineries alone could exceed 50,000 tons, instead of the 13,200 tons that EPA previously estimated.[v] EPA estimates that VOC emissions costs the public health an average of $900 to $4,000 per ton released, taking into account hospital visits, lost work days due to asthma attacks, etc.[vi] Using the midpoint of that range, the public health toll from refinery flares exceeds $120 million per year, based on the revised emission factors.

*  The industry has long relied upon EPA estimates to demonstrate that flares are minor emission sources that do not require additional control or permitting. That will no longer be possible.

  • Both regulators and the industry now have added incentives to recover and reuse flare gas instead of burning it off.  A 2013 report found that drillers in North Dakota are losing over a 100 million dollars a month by flaring natural gas instead of recovering it as product.[vii]


[i] U.S. Energy Information Administration, North Dakota Aims to Reduce Natural Gas Flaring (Oct. 2014) http://www.eia.gov/todayinenergy/detail.cfm?id=18451.

[ii] 42 U.S.C. § 7430.

[iii] Environmental Integrity Project, EPA Agrees to Review Outdated and Inaccurate Formulas for Estimating Toxic Emissions at Refineries and Chemical Plants (Feb. 2014) http://environmentalintegrity.org/archives/6587.

[iv] EPA, Critical Review of DIAL Emissions Test Data for BP Petroleum Refinery in Texas City, Texas, EPA 453/R-10-002, (Nov. 2010); Loren Raun and Dan W. Hoyt, City OF Houston, Bureau of Pollution Control and Prevention, Measurement and Analysis of Benzene and VOC Emissions in the Houston Ship Channel Area and Selected Surrounding Major Stationary Sources Using DIAL (Differential Absorption Light Detection and Ranging) Technology to Support Ambient HAP Concentrations Reductions in the Community (DIAL Project) (Jul. 2011).

[v] EPA calculated that refineries release about 13,200 tons of VOCs from flares every year based on data submitted by industry.  EIP has adjusted this information based on the EPA’s revised emission factor issued today.  The actual impact of emission factors maybe be different because there is very limited data on the percentage of facilities that report emissions using EPA’s emission factors and those that use engineering judgment and process knowledge to estimate the total amount of VOCs routed to a flare and then calculate emissions assuming that the flare achieves a 98% destruction efficiency.

[vi] Office of Management and Budget, 2006 Report to Congress on the Costs of and Benefits of Federal Regulations and Unfunded Mandates on State, Local, and Tribal Entities, 64 (Jan. 2007) (The per ton value of reducing VOC emissions are inflation adjusted for 2015).

[vii] Ernest Scheyder, Reuters, Exclusive: Bakken Flaring Burns More than $100 Million a Month (Jul. 29, 2013). http://www.reuters.com/article/2013/07/29/us-bakken-flaring-idUSBRE96S05320130729