Western wildfires pose a much broader threat to human health than to just those forced to evacuate the path of the blazes.
Smoke from these fires, which have burned millions of acres in California alone, is choking vast swaths of the country, an analysis of federal satellite imagery by NPR’s California Newsroom and Stanford University’s Environmental Change and Human Outcomes Lab found.
The monthslong analysis, based on more than 10 years of data collected by the National Oceanic and Atmospheric Administration, and analyzed down to the ZIP code level, reveals a startling increase in the number of days residents are breathing smoke across California and the Pacific Northwest, to Denver and Salt Lake City in the Rocky Mountains and rural Kentucky and West Virginia in Appalachia.
When looking at major U.S. cities, the analysis found the starkest increase in San Jose, California, where smoke days were up more than 400%. San Jose residents breathed smoke 45 days a year on average between 2016 and 2020. In Los Angeles and San Diego, the number of days with wildfire smoke increased 230% to 32 days a year in Los Angeles and 23 days in San Diego. Even the East Coast was not immune as prevailing winds carried smoke plumes from the Western United States and Canada thousands of miles away. In Philadelphia and Washington, D.C., our analysis found the number of days residents breathed wildfire smoke increased approximately 40% to over 20 days of smoke on average in a year.