The Los Angeles (LA) wildfires in January 2025 had a profound impact on air quality throughout the region. Smoke from wildfires can penetrate into our homes even when windows and doors are closed. It poses serious health risks given the significant amount of time we spend in our homes. The Harvard Healthy Buildings team worked with Airthings—a global technology company specializing in indoor air quality monitors — to study how the LA wildfires affected indoor air quality in nearby homes, using real-time data from 1,578 Airthings monitors installed in 1,048 homes across LA. Here are three key takeaways from the study:
1. LA Wildfires led to elevated indoor PM2.5 levels in homes. During the wildfires that began on January 7, more homes across LA had elevated, unhealthy PM2.5 levels (>35 µg/m3) compared to normal conditions. Exposure to such concentrations has been linked to adverse health impacts to the brain, heart, and lungs.
2. LA Wildfires impacted indoor air quality in homes more than 2 miles from the burn area. The impact of the wildfires extended to homes located more than two miles from the burn area. In these homes, there are clear increases in indoor PM2.5 levels after the onset of the wildfires.
3. Real-time air monitors are useful for wildfire response. These monitors worked well in detecting changes in home air quality during the wildfires. Monitoring indoor air quality and taking informed precautions are vital to protect health during wildfire events
What can you do with this information?
Other Resources