October 9, 2025
The Bay Area Air District voted Tuesday to lower the threshold for particulate pollution that triggers Spare the Air alerts banning most wood burning, in a change that could double the number of warnings annually, according to an Oct. 1 article from The San Francisco Chronicle.
Air regulators will issue alerts when forecasts predict fine particle pollution levels will reach 25 micrograms per cubic meter over 24 hours, down from the previous standard of 35 micrograms per cubic meter.
A growing body of health research has found that fine particulate pollution, known as PM2.5, contributes to a wide range of serious health issues, such as cancer, cardiovascular diseases and even dementia.
“There are no safe limits of fine particulate pollution,” Aaron Richardson, district spokesperson, said.
The district expects the number of alert days to increase from a historical average of 15 to between 19 and 41 per year.
The district’s vote comes one year after the U.S. Environmental Protection Agency issued tighter standards for PM2.5. That change meant that some air quality levels that would have previously been categorized as healthy are now listed as having some potentially negative health impacts.
Spare the Air alerts prohibit most wood burning across the Bay Area, except for households with no other source of heat that have registered with the district. Richardson said wood smoke is responsible for at least one third of fine particle pollution across the Bay Area during the winter months.
At the same time, the district’s 24 directors voted to waive fees for prescribed fires conducted by nonprofits and other entities. Public agencies already were exempt from fees. Richardson said that although prescribed fire generates smoke, it is an important step to reduce fuel loads and lower the risk of major wildfires.