Malheur National Forest goes into smoky detail

JOHN DAY, PRAIRIE CITY & HINES, OR – (Press Release from the Malheur National Forest)

Fire Information 101- Where there’s fire, there’s smoke. But is all smoke created equal? Prescribed fires and wildfires produce smoke. Smoke is made up of a complex mixture of gases and fine particles that are produced when wood and other organic fuels burn. Smoke primarily consists of carbon monoxide, carbon dioxide, water vapor, other chemicals, trace minerals, and particulate matter. The fine particulate matter in smoke is the greatest concern to public health because it is inhaled deep into the lungs, where it can cause irritation, inflammation, and shortness of breath and aggravate existing heart and lung diseases.

So how does smoke from prescribed fire compare to smoke from wildfire? Prescribed fires must be planned carefully to keep the smoke they produce at acceptable levels. Managers can predict the direction of smoke plumes by relying on weather reports and other data. Managers burn only under strict weather conditions that minimize smoke formation and problems. Occasionally, smoke from a prescribed fire may accumulate in a community, but any impacts are typically light and not long lasting.

Wildfires, however, burn under uncontrolled and unplanned circumstances, making it difficult to manage how much smoke is produced and where it goes. The primary factor in determining the generation of smoke is the amount of vegetation consumed. Vegetation consumption depends on the type of fuel (grass, trees, dead fuel such as woody debris, etc.), amount of dead fuel, fuel moisture content, size of fuel, topography, duration of the fire, air temperature, relative humidity, and wind speed. Wildfires typically occur during the summer months, when fuels are drier and the likelihood of adverse weather conditions (high temperatures, low relative humidity, and sustained wind speeds) is greater. Under these conditions, wildfires consume more vegetation on a per acre basis than prescribed fires, resulting in more smoke emissions. As smoke emissions increase, the concentration of particles in the air increases.

Smoke from Oregon’s largest 2021 fire, the Bootleg Fire, reached all the way to the East Coast. Even more toxins may be lurking in wildfire smoke from fires that burn through neighborhoods, consuming homes containing manufactured items such as electronics, insulation, and plastic.

In general, wildfires are far more likely to result in harmful air quality and public health impacts than prescribed fires because they are unplanned and typically are much larger. Wildfires also last longer and burn and consume more vegetation per acre than prescribed fires.

For more information on the Malheur National Forest please call one of our offices or visit: https://www.fs.usda.gov/malheur/

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