On September 11, smoke from the Southern California fires blew into Big Bear, causing local air quality monitors to record off-limit levels of particulate pollution.
Officials report air quality on a color-coded scale, with green indicating “good” and maroon indicating “hazardous” conditions. An air quality index above 150 is considered unhealthy for everyone; anything above 300 is considered hazardous.
On Wednesday, Big Bear’s AQI for fine particulate matter (PM2.5) reached an alarming daily average of 593.
That was the third-highest AQI measured in Southern California since at least 1999, according to data from the National Air Quality Center.
The first and second worst days for air quality ever recorded in Ventura County occurred during the largest wildfires in state history in 2017. On December 6 and 8, the Ojai monitoring station recorded daily average AQIs of 961 and 906, respectively.
Preparations have been underway for weeks for the hills and mountains of Southern California to burn.
Between September 5th and 9th: The Rhine Fire in San Bernardino County, the Bridge Fire in San Bernardino and Los Angeles Counties, and the Airport Fire in Orange County.
The fire started in Highland on Sept. 5 and quickly spread through the mountains toward Big Bear. A 34-year-old Norco man is suspected of starting the blaze.
As of Friday, flames had scorched more than 38,000 acres in the San Bernardino Mountains, and while the fires have yet to reach any resort areas, fine ash particles and smoky haze have clouded the skies over the mountainous region.
High winds have billowed smoke across the Big Bear Valley, forcing towns to close, with much of the region still closed and evacuation orders in place for some towns.
“I think all of the agencies are doing everything they can to try and get this fire under control so that a lot of areas aren’t destroyed,” Big Bear Lake Mayor Eric Sand said.
Particulate pollution, including from wildfire smoke, is dangerous to nearly everyone, including pregnant women, young children, older adults and adults with underlying medical conditions.
Fine particulate matter can have more adverse effects on people’s health than other pollutants, such as ozone. The tiny particles, about , can easily penetrate the lining of the lungs and enter the bloodstream. A 2023 study linked long-term exposure to PM2.5 to .
“We’re concerned about the differential impact of wildfire smoke, where even if wealthier people are exposed to the same smoke as lower-income people, lower-income people are less able to protect themselves,” said Dr. John Balmes, commissioner of the California Air Resources Board. “It’s where the smoke plume goes that has the biggest impact.”
In August, Balmes and colleagues, environmental health sciences researchers at the University of California, Berkeley School of Public Health, published a paper revealing that they now have more data than other communities.
During wildfire season, experts encourage Californians to keep an eye on local air quality monitoring reports, available from the U.S. Environmental Protection Agency and services like .
“At the very least, staying indoors and closing all the windows and doors will greatly reduce your exposure to air pollution,” said the UCLA professor of atmospheric and oceanic sciences. “If you’re going to exercise, make sure you’re outside in the dark orange, red, and dreaded dark purple-brown colors that are used for a very high Air Quality Index (AQI).”
