Air Pollution Progress Still Undermined by Western Wildfires

Research Report by Climate Central
August 2018


This report is part of “Breathing Fire,” a series of research reports and journalism features by Climate Central.
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In more than half of the states in the American West, the largest wildfire on record for each state has occurred since 2000. Large wildfires damage landscapes, property, infrastructure, and local economies. They can claim lives directly, and cause or exacerbate serious health problems by releasing significant quantities of air pollutants, including the fine particles known as PM2.5 (particulate matter smaller than 2.5 microns in diameter). These harmful effects extend well beyond where the fire itself burns. Though climate change is not the sole factor increasing the size and frequency of western wildfires, it is an important contributor.

Climate Central previously analyzed trends in PM2.5 concentrations for California’s Central Valley between 2000 and 2016. This report updates that analysis and extends it to three additional states — Idaho, Oregon, and Washington — all of which are also plagued by worsening wildfires in a warming world.

Update: California’s Central Valley

In 2017, Climate Central analyzed trends in annual PM2.5 concentrations between 2000 and 2016 for the Sacramento Valley and the San