Wildland Fire Smoke, Air Quality, and Health

INSIGHTi

Wildland Fire Smoke, Air Quality, and Health

August 13, 2026

Wildland fire smoke is a complex mixture of gases and fine particles produced by burning materials

during wildland fire events that temporarily degrades air quality over long distances, creating health

concerns and decreasing visibility. Wildland fire smoke affects the public and fire personnel, and may

impose a disproportionate risk on sensitive populations such as children, older adults, and those with

certain chronic conditions. During 2023 and 2026, weather conditions transported Canadian wildfire

smoke hundreds of miles into the United States, driving responses from the public and some Members of

Congress.

Wildland Fire Smoke and Health

Particulate matter is the principal pollutant of concern from wildland fire smoke. Wildland fire smoke,

including smoke from prescribed burns (planned fires burning under supervision) and wildfires

(unplanned fires and escaped prescribed burns), releases fine particles (less than 2.5 microns, or

“PM2.5”). The U.S. Environmental Protection Agency’s (EPA’s) National Emissions Inventory identifies

wildland fires as a major contributor of these fine particles and other pollutants. Fine particles can

penetrate deeply into the lungs and may contribute to a range of health effects, including eye irritation,

sore throat, coughing, breathing difficulties, worsening of preexisting heart and lung disease, and

increased premature mortality.

Wildland fire smoke also includes carbon monoxide, hazardous air pollutants, and emissions that

contribute to the formation of ground-level ozone, a lung and airway irritant. The chemical composition

of smoke depends on various factors, including burn conditions (e.g., fire temperature) and type of

materials burned (e.g., vegetation or structures).

Research links wildland fire smoke exposure to health complications, including respiratory,

cardiovascular, and potential pregnancy impacts; reduced lung function in subsequent years; and

increased risk of respiratory infections in exposed infants and influenza across age groups. While smoke

may affect the health of any exposed individual, sensitive populations—children, people who have

chronic conditions, pregnant women, and the elderly—are more vulnerable.

Wildland firefighters are regularly exposed to pollutants in wildland fire smoke, including carcinogens.

Less is known about cumulative and long-term exposure to wildland fire smoke. In 2026, the U.S. Forest

Service within the U.S. Department of Agriculture and the U.S. Wildland Fire Service within the U.S.

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Department of the Interior updated policies in an effort to reduce smoke exposure for wildland fire

personnel.

Air Quality Requirements and Wildland Fires

The Clean Air Act (CAA) is the principal statute addressing air quality concerns. The CAA requires EPA

to establish minimum national air quality standards to protect health. EPA has set and periodically revised

national ambient air quality standards (NAAQS) for six “criteria” air pollutants, including some that are

in wildland fire smoke. Under the CAA, states have primary responsibility for assuring compliance with

NAAQS and establishing state implementation plans intended to meet these standards. Measurements

from a national network of air quality monitoring stations, in combination with modeling analyses, inform

NAAQS compliance determinations.

The national monitoring network may detect smoke from wildland fires, sometimes exceeding the

NAAQS. The CAA allows EPA to exclude air quality data from regulatory decisions if air quality is

demonstratively influenced by “exceptional events,” such as wildland fires and certain natural events (42

U.S.C. §7619(b)). To exclude prescribed burn-impacted air quality data from regulatory decisions,

individuals and agencies that conduct prescribed burns must adhere to the exceptional events rule by

demonstrating appropriate smoke management procedures.

Wildland Fire Smoke Response

Wildland fire smoke response strategies include air quality monitoring, smoke forecasting, timely

communication of air quality conditions and related health risks, and measures to avoid smoke. Federal,

tribal, state, and local agencies contribute to these tasks.

EPA and other agencies have developed tools to measure air quality conditions and alert the public. For

example, EPA manages AirNow, a multiagency website that reports air quality based on monitoring data

received on a regular basis from state, local, and federal agencies. AirNow reports air quality information

using the color-coded Air Quality Index (AQI), a nationally uniform index. EPA calculates the AQI for a

criteria pollutant based on the ambient concentration of that pollutant. The higher the AQI, the greater the

pollution level. EPA’s AirNow mobile app can send phone alerts when AQI exceeds a user-chosen

threshold, and its EnviroFlash service provides email alerts. The National Weather Service issues air

quality alerts when the AQI is unhealthy. States and local agencies may share alert information with local

media outlets.

To help protect health near wildland fires, the Forest Service’s Interagency Wildland Fire Air Quality

Response Program (IWFAQRP) may deploy trained specialists called Air Resource Advisors (ARAs) to

monitor and forecast local air quality conditions and help develop smoke management strategies. ARAs

also use computer modeling to estimate pollution levels. The IWFAQRP and EPA lend smoke particulate

monitoring kits to ARAs and firefighting agencies to monitor wildland fire emissions. In 2026, the

program had more than 70 ARA deployments. EPA also lends supplemental and educational air quality

monitors.

The federal government provides other resources to help individuals and local officials who encounter

wildland fire smoke. For example, EPA publishes resources online, including a guide for public health

officials. EPA collaborated with the American Society of Heating, Refrigerating, and Air-Conditioning

Engineers (ASHRAE) to develop guidelines and best practices for building design and operation to

reduce smoke impacts. EPA also provides assistance to certain nonfederal entities for projects that seek to

improve public health protection during wildland fire smoke events through its Wildfire Smoke

Preparedness in Community Buildings grant program.

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Issues for Congress

The federal government currently engages in measures to protect the public from wildland fire smoke

through air quality monitoring, public communications, financial and technical assistance, and other

means. Congress may consider options for maintaining or improving air quality monitoring networks,

smoke models, and public communications to help inform smoke management and public health

responses. Congress could clarify the eligibility of prescribed burns as exceptional events and reduce the

burden and cost to demonstrate an event. Congress may also consider supporting research into fields

related to smoke and health, such as respiratory protection devices, building technologies, medical

research, or other topics.

Author Information

Alicyn R. Gitlin

Analyst in Natural Resources Policy

Omar M. Hammad

Analyst in Environmental Policy

Disclaimer

This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan shared staff

to congressional committees and Members of Congress. It operates solely at the behest of and under the direction of

Congress. Information in a CRS Report should not be relied upon for purposes other than public understanding of

information that has been provided by CRS to Members of Congress in connection with CRS’s institutional role.

CRS Reports, as a work of the United States Government, are not subject to copyright protection in the United

States. Any CRS Report may be reproduced and distributed in its entirety without permission from CRS. However,

as a CRS Report may include copyrighted images or material from a third party, you may need to obtain the

permission of the copyright holder if you wish to copy or otherwise use copyrighted material.

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