What Are Fugitive Emissions? Definition and Impact

steam being released from pipes in an industrial setting

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Fugitive emissions are gases and vapors accidentally released into the atmosphere. Most fugitive emissions come from industrial activities, like factory operations. These emissions contribute to climate change and air pollution. Some fugitive emissions, like the release of ethylene oxide from medical sterilization facilities, pose a significant health risk to people living nearby. Other fugitive emissions, like methane unintentionally released by the oil and gas industry, add a greenhouse gas to the atmosphere that's over 80-times stronger than carbon dioxide. In the United States, fugitive emissions are primarily regulated by the Environmental Protection Agency, or EPA, under the Clean Air Act.

Types of Fugitive Emissions

Fugitive emissions come in many forms including dust, fine particles, and aerosols. Of these, the most environmentally impactful fugitive emissions are greenhouse gases, such as refrigerants and methane.


A truck spraying water onto dirt on a construction site.
Water is sprayed onto unpaved areas to prevent vehicles from kicking up dust.

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Dust, or fine particles of soil and other organic material, is unintentionally released from driving on unpaved roads, tilling of agricultural fields, and heavy construction operations. Once kicked-up, dust can contribute to air pollution. Fugitive dust can cause people to have difficulty breathing, chronic respiratory illness, and lung disease. It can also increase the risk of traffic accidents due to reductions in visibility and reduce agricultural productivity by shielding sunlight. In the United States, the arid and semi-arid areas in the southwest are especially at risk of releasing fugitive dust from ongoing development.

On construction sites, dust can be managed by frequently wetting unpaved areas. When wet, fine particles on the ground are too heavy to be kicked up during the operation of construction machinery. In agriculture, dust can be reduced by the planting of cover crops, irrigation, reducing the frequency of tilling, and combining tractor operations.


An air compressor next to a building used as part of an air conditioning system.
Air conditioning systems use refrigerants, which can be released as fugitive emissions.

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Various types of chlorofluorocarbons, or CFCs, were commonly used in the 20th century as refrigerants. The production of CFCs was banned in the United States and in many countries around the world in the 1990s. However, the accidental release of these environmentally damaging chemicals continues today from the ongoing use of CFCs in outdated equipment and the use of recycled CFCs in fire suppression systems. In 2012, there was an unexpected and persistent increase in global emissions of one particular type of CFC, CFC-11, which contributes a quarter of all ozone-depleting chlorine that reaches the stratosphere. International efforts to reduce the fugitive release of CFC led to rapid declines of atmospheric CFCs in 2019 and 2020.


A woman breathing out of a nebulizer under the supervision of a doctor.
Some of the aerosolized medicine delivered by nebulizers can escape into the surrounding air as fugitive emissions.

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Various aerosols commonly used in modern medicine result in fugitive emissions. One source of these emissions is nebulizers, which help deliver aerosolized drugs to patients' lungs. Nebulizers are primarily used to treat respiratory diseases. However, in the process of delivering these aerosols to a patient, some accidentally escape. These fugitive emissions can remain in the surrounding air for several hours, putting people at risk of accidentally inhaling medication.

Oil and Gas

a fracking rig in in a flat landscape
The natural gas wells created by fracking are an important source of fugitive methane emissions.

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Oil and gas wells are a substantial source of fugitive emissions. In 2018, a natural gas well in Ohio operated by a subsidiary of ExxonMobil leaked millions of cubic feet of methane into the atmosphere over the course of twenty days. This massive release of fugitive emissions was detected by a satellite's routine global survey — the first such leak to be detected using satellite technology. Methane leaks are common due to the United States' shift from coal to natural gas, the latter of which produces fewer greenhouse gas emissions when burned. However, the accidental release of methane during natural gas extraction may counteract natural gas's emissions advantage over coal.

Additional fugitive emissions come from the oil and gas industry's abandoned wells. Abandoned, uncapped wells are also known to release methane into the atmosphere well after they close. In some cases, fugitive emissions are released by poorly or improperly sealed wells.

Ethylene Oxide

Ethylene oxide is used to manufacture a variety of chemicals, like plastics, textiles, and antifreeze, and is used to sterilize foods, spices, and medical equipment. Since the 1980s, ethylene oxide has been known to cause cancer in animals based on studies conducted on mice and rats. It is considered to be a known carcinogen by the US EPA and the CDC. During a recent review of the hazardous emissions, the EPA found the fugitive release of ethylene oxide to be the most significant driver of unacceptable health risks resulting from all hazardous air pollutants in the United States.

How Are Fugitive Emissions Regulated?

Leakage of steam in heat pipeline. Steam outgoing from the rusty tube with valve
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Most fugitive emissions are regulated by the EPA . In some cases, state and local agencies apply further regulations to the release of fugitive emissions.

Dust Regulations

Many development projects are required to go through the National Environmental Policy Act, or NEPA, which includes an assessment of a project's anticipated air quality impacts. If a project is expected to have "significant" impacts on air quality, such as through the fugitive release of dust, measures to mitigate the effects may be required by the EPA. Some states, like California, have an additional environmental review process that applies air quality standards to certain projects, including projects not required to go through the NEPA process. These air quality regulations include measures to reduce the risk of fugitive emissions.

CFC Regulations

Refrigerators and air conditioning devices used to use various chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). After the discovery that these aerosols were putting holes in Earth's ozone layer, the international ratification of the Montreal Protocol in 1988 and amendments to the Clean Air Act in 1990 phased out the use of these and other environmentally damaging chemicals. Hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) are used today instead.

Similarly, halon was once commonly used for fire suppression. Halon can quickly suck the oxygen out of a room, rapidly stopping a fire. However, in addition to being deadly to people, halon also has an ozone-depleting effect. The EPA began phasing out the production and import of new halon in 1994. Halon blends were banned in 1998. Today, only recycled halon is used for specific fire suppression applications, such as on aircraft and for oil and gas exploration operations. The EPA only allows the release of halon during the testing, maintenance, and repair of halon-containing equipment. The EPA has the authority to levy heavy fines against those who release halon and other ozone-depleting substances accidentally or without EPA authorization.

While the production of many ozone-depleting substances is banned in the United States and a number of other countries around the world, old products containing these greenhouse gases remain in old refrigerators and air conditioning units. As these decades-old pieces of equipment deteriorate, the CFCs they hold are often released as fugitive emissions. One of these ozone-depleting substances, CFC-12, traps nearly 11,000 times the heat of carbon dioxide. Given the environmental hazard created by these old, often forgotten refrigerants, the recycling of old CFCs is now a part of the carbon-offset market: people can exchange their old refrigerants for money.

Monitoring Requirements for Fugitive Emissions

The EPA requires certain entities, like active oil wells and compressor stations, to perform semi-annual or annual tests for fugitive emissions. Once a source of fugitive emissions is discovered, the EPA requires repairs to be made within 30 days. In 2020, the EPA eliminated monitoring requirements for "low production" well sites — those producing less than 15 barrels per day. Restrictions on incidental methane emissions were also reduced, which even oil industry proponents criticized.

The EPA similarly regulates the unintentional release of ethylene oxide. However, in 2016 ,the EPA increased allowable exposure levels by nearly 50-fold. In 2018, research on a Michigan sterilization facility found local ethylene oxide levels to be 100 times the EPA's 2016 limit and 1500 times State's limit. The study concluded the high ethylene oxide exposure levels were largely caused by uncaptured fugitive emissions. By order of the State of Michigan's Department of Environment, Great Lakes, and Energy (EGLE), the facility was forced to stop using ethylene oxide by January 2020 and pay a $110,000 penalty to the State of Michigan.

Future Outlooks

The impact of fugitive emissions on climate change and human health has gained attention in recent years.

Carbon Offset Market for CFCs

In the United States, carbon offset markets are expected to continue filling some of the gaps in the regulation of CFC fugitive emissions by incentivizing the removal of now-banned greenhouse gases. However, carbon offset projects must wait for credits to sell to make a return on investment. For developing countries, the need for capital upfront may be a barrier to implementing effective carbon offset programs for CFCs.

Methane Emissions

According to a 2018 report published by Climate Chance, the oil and gas industry is the primary producer of fugitive emissions. The report also found the United States to be the second-largest producer of fugitive emissions of the 10 countries analyzed. The Biden Administration has moved to review, and potentially remove, some of the Trump administration's rollbacks to the Clean Air Act, including decisions that reduced restrictions on allowable methane emissions from the oil and gas industry.

Additional satellites are scheduled for launch in the coming years to bolster global monitoring of fugitive emissions from the oil and gas industry. According to the Environmental Defence Fund (EDF), which plans to launch a new methane-monitoring satellite in 2022, fugitive emissions from the oil and gas industry are up to 60% higher than what the EPA has found.

Ethylene Oxide Emissions

State regulations of fugitive ethylene oxide emissions continue to expand as the public becomes more aware of the health risks associated with the chemical. For example, Illinois passed two new laws regulating ethylene oxide in 2019 making the state's ethylene oxide emissions standards the strictest in the country. Similarly, Georgia is working with sterilization facilities to implement voluntary reductions in ethylene oxide emissions. Meanwhile, the State of Texas took its ethylene oxide legislation in the opposite direction by increasing the allowable limit from 1 part per billion (ppb) to 2.4 ppb in 2020.

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