After nearly four weeks of burning, the fires in Los Angeles are almost fully contained, and cleanup is underway. But as the dust literally settles, people in LA are left with major questions, like: What is actually in the ash? What’s in the air? And how do I stay safe?Flora Lichtman talks with two experts in public health and toxic substance exposure about the chemicals left behind after an urban fire as well as what science needs to be done to fully understand the issue. She speaks with Dr. Rima Habre, associate professor of environmental health and spatial sciences at the University of Southern California in Los Angeles; and Dr. Mark Wilson, director of exposure science at Chemical Insights Research Institute (CIRI) in Marietta, Georgia.Transcript for this segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.