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Smoke from wildland fire is a significant source of air pollution emanating from National Forest lands. It can pose potential health, visibility, safety, and nuisance problems. Forest managers, fire managers, and air resource specialists must address these issues when and where appropriate to minimize smoke impacts to public health and welfare.

National Forest lands contain ecosystems substantially departed from natural fire regimes, as well as spectacular scenery that can be impacted by smoke from unplanned and planned (prescribed) fires. Decades of aggressive wildfire suppression and other land use practices have given rise to ecosystems with unnaturally heavy fuel accumulations, proliferation of invasive exotic species, and unnaturally large and severe wildfires. Large wildfires produce more smoke and air pollution annually than prescribed fires. Nationally, the restoration of fire-adapted ecosystems to effectively lessen the likelihood of large wildfires is a high priority.

Public and Firefighter Health

The chemicals in smoke that cause the most hazard to human health are carbon monoxide, aldehydes, and tiny particles of solid matter that are small enough to be inhaled. Particulate matter is the main pollutant of concern to the public as carbon monoxide, aldehydes, and the hundreds of other compounds emitted by wildland fires are found in very low concentrations at short distances away from a fire.

Coarse particles about 5 to 10 microns in diameter deposit in the upper respiratory system. Fine particles less than 2.5 microns in diameter (PM 2.5) can penetrate much deeper into the lungs. Exposure to fine particles in the air increases the chances of respiratory and cardiovascular illness. Even relatively brief exposures to particulate matter may aggravate asthma and bronchitis and cause heartbeat irregularities and heart attacks. Some particulate pollution also has carcinogenic effects to humans. These fine particles deposit in the alveoli where the body's defense mechanisms are ineffective in removing them. People with heart or lung disease, children, and the elderly are considered sensitive and are at a greater risk from exposure to particulate matter. The effects of breathing wildland fire smoke include eye and throat irritation, shortness of breath, headaches, dizziness, and nausea. For more information on health effects of particulates visit http://www.epa.gov/airnow/particle/pm-color.pdf.

Public exposure to smoke is a concern because a large proportion of wildland fire smoke emissions is PM 2.5. Prescribed fire managers need to identify smoke-sensitive areas such as communities, hospitals, highways and areas already in nonattainment for particulate matter or ozone, and use appropriate mitigation and evaluation techniques to minimize smoke impacts. Weather, climate, and air quality monitoring data are used by fire managers to customize smoke management techniques as needed. These data can also help local health departments alert citizens about the effects of smoke and where it may travel.

Wildland firefighters are exposed to smoke for various lengths of time. The first firefighters on the fire are typically closer to the actual fire and breathe a lot of smoke, but typically for short periods of time. Firefighters on large fires that take days or even months to control usually work further away from the actual fire, but for longer periods of time. Recent studies show that smoke is a greater hazard for firefighters when the wind sends smoke in their direction, when they spend long periods of time putting out smoldering stumps and logs, and when initial attack firefighters have to surround a fire quickly. Extended periods of smoke exposure in base camps may also pose hazards to firefighters. Battery-powered smoke samplers that firefighters can wear are available for fire managers. For more information, visit http://www.fs.fed.us/pnw/fera/research/smoke/exposure.shtml