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Fighting Fire with Fire: The EPA Must Harness Beneficial Fire to Reduce PM2.5 Emissions

Sara Ann Clark and Jenna N Archer


  • Discusses the need for beneficial, or prescribed, fire in order to combat wildfire.
  • Analyzes why the EPA must commit to enabling expanded beneficial fire use to protect public health and welfare.
  • Looks at why the EPA should recognize smoke from cultural burning is exempt from the CAA.
Fighting Fire with Fire: The EPA Must Harness Beneficial Fire to Reduce PM2.5 Emissions
RichLegg via Getty Images

In January, the U.S. Environmental Protection Agency (EPA) proposed to modify the Clean Air Act (CAA) National Ambient Air Quality Standards (NAAQS) for fine particle pollution (PM2.5), by lowering the annual standard to between 9 and 10 micrograms per cubic meter and retaining the daily standard but accepting comments on lowering it to 25 micrograms per cubic meter. Reducing PM2.5 emissions is necessary to protect public health, particularly communities of color and low-income communities, which are most adversely impacted. But this rule will have unintended consequences, frustrating necessary efforts to increase the use of prescribed fire, cultural burning by Tribes and Indigenous fire practitioners, and wildfire managed for resource benefit (beneficial fire). 

Climate change and decades of fire suppression have increased the prevalence and severity of wildfires. Wildfire smoke is now one of the greatest contributors to PM2.5 emissions, posing a critical threat to public health. Beneficial fire is our greatest tool to combat wildfires. 

Beneficial fire use is one of the best tools to reduce wildfire smoke and its impacts.

The growing wildfire crisis threatens to overwhelm recent progress on ensuring cleaner air. Expanding beneficial fire use is one of our few tools to reduce and mitigate wildfire impacts.

Studies show beneficial fires produce fewer, less harmful emissions than wildfires. Beneficial fire generally retains overstory trees and vegetation, through the initial application of beneficial fire and subsequent wildfires. But megafires consume that vegetation, as shown in the unprecedented die-off of giant sequoias in recent years. Wildfires also often consume homes, cars, and other man-made material, resulting in larger smoke plumes containing toxic chemicals.

Beneficial fire also enables better mitigation of public health impacts. Practitioners and agencies can plan prescribed burns in advance to reduce community impacts. This includes conducting burns on days with favorable meteorological conditions, like wind patterns that disperse smoke away from populated areas and sensitive locations like schools and hospitals. And air agencies work with communities to avoid smoke exposure through masking, filtration, clean air spaces, and temporary relocation.

The EPA’s reliance on the Exceptional Events Rule is misplaced.

The EPA has taken the position that the Exceptional Events Rule will adequately address these issues. But the existing rule has failed to create a navigable pathway to expand beneficial fire use.

Under the Exceptional Events Rule, air agencies may request the EPA exclude emissions data when taking regulatory actions by demonstrating that an “exceptional event” caused those emissions. 40 C.F.R. §§ 50.1, 50.14, 51.930. To make an Exceptional Events demonstration, the state air agency must show the event “affect[ed] air quality,” was “not reasonably controllable or preventable,” was “caused by human activity that is unlikely to recur at a particular location or a natural event.” 40 C.F.R. § 50.14(b)(3)(i).

In theory, beneficial fires can qualify as exceptional events, but in practice, the rule created barriers to beneficial fire use. In the seven years since its adoption, no air regulators have ever used the Exceptional Events Rule for prescribed fire.

The Exceptional Events Rule creates a perverse incentive, making it easier for air agencies to deny requested approvals to burn than to agree to preparing an Exceptional Events demonstration. Unlike Exceptional Events demonstrations for wildfires, where states have no choice but to prepare to address unplanned exceedances, air agencies can avoid preparation of Exceptional Events demonstrations for beneficial fire altogether by disallowing prescribed burns in the first place.

This is largely because Exceptional Event demonstrations also require expensive and technical submissions by air agencies. EPA guidance documents require extensive data and statistical analysis that can create months, if not years, of work and cost tens of thousands of dollars to prepare. Showing a “clear causal connection” is among the most onerous.

The EPA must commit to enabling expanded beneficial fire use to protect public health and welfare.

To accomplish its public health objectives, the EPA must take a dual track: tightening the PM2.5 NAAQS and enabling greater beneficial fire use. Ignoring this need will commit the country to a future of increasing wildfire smoke and associated health impacts, especially in rural communities adjacent to wildfire-susceptible landscapes. This would be contrary to the EPA’s mission to protect public health and welfare.

We propose three recommendations for the EPA to implement through further guidance or rulemaking in collaboration with stakeholders.

First, if the EPA reduces the PM2.5 NAAQS as intended, more counties will fall into nonattainment or more severe nonattainment status. As a result, many air agencies will be tasked with preparing new State Implementation Plans (SIPs) and developing new strategies for reducing PM2.5 pollution. This involves making tradeoffs between different emissions sources. If states retain existing limitations for some sources, they must impose more stringent limitations on others. This could lead states to provide an insufficient “budget” for beneficial fire when developing new SIPs.

The EPA should issue a revised implementation rule that ensures future SIPs enable beneficial fire. It should require air agencies to analyze the amount and location of beneficial fire programs necessary to mitigate wildfire risk, including the fire return interval departures, location of homes and infrastructure, and feasibility of implementation. When considering how to cut emissions, the EPA should require air agencies to look first to other anthropogenic sources, like tailpipes, industrial facilities, and energy generation, before limiting beneficial fire smoke.

The EPA should then require air agencies to develop strategies to facilitate permitting for beneficial fire programs. Air agencies should have leeway to design these programs, with the EPA offering guidance and support for Exceptional Events demonstrations when needed.

Ultimately, SIPs must demonstrate air agencies are taking all reasonable steps to mitigate risks and potential impacts of beneficial fire, including through public communication and engagement; provision of air filters, clean air spaces, and masks; and adequate healthcare resources.

Second, the EPA should reexamine the Exceptional Events Rule with respect to beneficial fire use. The EPA should develop a model with basic inputs (such as acres burned, forest type, percent fuel consumption, prevailing wind, and distance from air monitor), which air agencies could complete with minimal investments. These models should create a presumption in favor of finding a clear causal connection, rebuttable only by substantial evidence. The EPA should also work with air agencies and practitioners to establish mechanisms to allow Exceptional Events demonstrations for entire beneficial fire programs. The 2016 Exceptional Events Rule allows air agencies to combine multiple events in one demonstration but lacks clarity on how to do so.

The EPA should also take advantage of speciated particulate monitoring—technology that can determine the source of particulate matter pollution. It should evaluate how to use speciation data to quickly and reliably demonstrate the “clear causal” relationship, reducing burdens on air agencies.

Third, Tribes and Indigenous people have practiced cultural burning since time immemorial. Ecosystems evolved alongside these practices into the fire-dependent places we know today. Smoke from these practices is properly considered part of natural background conditions that have been part of the environment since before the founding of the United States.

The EPA should recognize smoke from cultural burning is exempt from the CAA, and states cannot exert regulatory control over cultural burning. The CAA recognizes there may be circumstances where federal facilities should be exempt from CAA compliance for actions in the “paramount interest” of the United States. 42 U.S.C. § 7418(b). Given the paramount importance of cultural burning as a matter of cultural and environmental justice and of ecological necessity, this exemption should apply here.

Moreover, the EPA allows different treatment of culturally important activities. In the Exceptional Events Rule, fireworks displays may be excluded from monitoring data if the “use of fireworks is significantly integral to traditional national, ethnic, or other cultural events.” 40 C.F.R. § 50.14(b)(2). The EPA should similarly exempt cultural burning.

Wildfire smoke is one of our greatest challenges with respect to fine particulate matter. The EPA must take decisive action to support beneficial fire to combat the growing threat of wildfires and accomplish its mission of protecting the public health and welfare.

There is no no-fire future: there is only the opportunity to choose between beneficial fire use for lower severity wildfires and healthier ecosystems and communities, or the continued rise of destructive megafires.