Dear Doctors: We live in the fire zone in Altadena, California. After the evacuations ended, we came home, and now my throat is constantly sore. There’s no smoke smell, but my husband says the air can still be unhealthy. Why would that be? The air quality numbers are good, so it’s confusing.
Dear Reader: We are near one of the fire zones in Southern California and are sadly familiar with the ongoing aftermath. Over the course of 24 days, fire tore through 60 square miles, destroyed more than 16,000 homes and businesses and damaged thousands more. At least 29 people died, and many more, including rescue workers, were injured. Now the flames are out, but the health dangers continue. This is due to fine particulates released by the fires. We touched on this in a column last month, but your question allows a more detailed look at the issue.
Particulates are the microscopic bits of burned materials that become suspended in wildfire smoke. Their extremely small size means they can be inhaled into the deepest recesses of the lungs. These are the alveoli, which are minute air sacs clustered at the ends of the bronchial tubes. The delicate membranes of these air sacs are where the oxygen we breathe in enters the bloodstream and the carbon dioxide produced by metabolic processes exits. To get a sense of just how small alveoli are, an adult has about 240 million in each lung.
The particulates released in urban fires differ from those generated by forest fires. In urban fires, particulates come from the vast array of manmade materials found in the built environment. They include building materials, appliances, electronics, plastics, vehicles, batteries, gasoline, propane, paints, stains and solvents, cleaning products, pesticides, carpets, wood and tile floors and furnishings. As these burn, dangerous substances are released into the air. They include heavy metals such as lead, zinc and chromium; toxic chemicals such as formaldehyde, benzene, ethylene glycol-toluene, chlorine and asbestos from older homes; and an array of carcinogens known as polycyclic aromatic hydrocarbons, or PAHs.
The AQI, or air quality index, warns about common pollutants such as ozone, carbon monoxide, sulfur dioxide and nitrogen dioxide. However, many of the particulates generated in urban fires are outside of its scope. That’s the disconnect -- and the ongoing health risks -- that your husband is referencing. Wildfire particulates mix with the ash and soot that fall to the ground. When blown by wind or disturbed during debris removal, they can once again become airborne. Updated air quality specific to wildfire particulates is available at fire.airnow.gov.
People returning to burn areas are advised to take precautions for several months. Keep windows and doors closed whenever there’s a smoky smell. Use an appropriately sized air purifier that has a HEPA filter, and change the filter often. When it’s windy, and when debris removal occurs, use an N95 mask while outdoors.
Wildfire particulates are known to ramp up inflammation throughout the respiratory tract. If the throat irritation you are experiencing doesn’t clear up, please check in with your health care provider.
(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)
