heezing. They can also include rapid or irregular heartbeat and excessive fatigue.

These symptoms typically pass when the smoke leaves, but health risks remain.

Health problems may follow smoke exposure

Growing evidence shows that effects can linger or lead to persistent health problems. Research is beginning to link exposure to PM2.5 pollution, including wildfire smoke, with dementia, Alzheimer's, preterm birth, lung and brain cancer and other illnesses.

People with pre-existing conditions, such as lung and heart disease, are more vulnerable to the effects of wildfire smoke. They can be at risk of an acute event, like a stroke or heart attack, during a wildfire.

Children and infants are also more vulnerable to wildfire smoke. A study of smoke exposure on the lungs of infant monkeys during a wildfire found impacts on their immune systems and lung functions.

But even healthy people aren’t spared: A UC Davis study found that when blood samples were taken during wildfire events in Northern California, healthy volunteers had elevated levels of inflammatory markers.

Companion animals, including cats and dogs, can also be impacted by wildfire smoke. The American Veterinary Medication Association recommends keeping pets indoors as much as possible during smoky conditions.

Why urban wildfire smoke and ash is more toxic

Traditional wildfires burn mostly biomass, such as trees and shrubs. Wildfires like the ones currently burning in Los Angeles occur in what’s known as the wildland-urban interface.

“These wildfires are different because they are burning houses and structures,” said Anthony Wexler, a distinguished professor and the director of the UC Davis Air Quality Research Center. “In houses, you have plastic, metal, solvents, carpets, paint, pesticides, cars with rubber and metal and everything else. And when those burn, they create more toxic smoke and ash,” Wexler said.

Wear a mask in smoky or ashy conditions

According to Pinkerton, during smoky conditions, individuals who leave their homes should wear a well-fitting mask with good filtration and a tight seal against the nose and mouth. N95 or P100 masks offer good filtration, but KN95 masks can also be effective if those aren’t available. Wildfire ash also poses a health risk. People should wear masks around any burned area.

Children ages 2 years and older can wear masks; however, N95 masks don’t come in children’s sizes. Older children may be able to wear the small size of an adult N95 mask. For kids and toddlers, the New York Times Wirecutter column has a list of recommended KN95 masks.

10 ways to protect your health when the air is smoky

• Check real-time air quality index levels on AirNow or PurpleAir
• Avoid strenuous exercise outdoors
• When traveling by car, put the air on recirculate to keep the smoke out as much as possible
• Wear a well-fitting mask when outdoors. N95 or P100 masks offer the most protection, but KN95 masks can also be effective
• Close all windows and doors in your home
• Run your HVAC (heating, ventilation, and air conditioning) on recirculate and use a new filter
• Use an air-purifying device; those with HEPA filters are the most effective
• Make your own air filter (better known as a Corsi-Rosenthal box) using a box fan (instructions here)
• Avoid vacuuming or frying food, which can decrease air quality in the home
• Avoid smoking or vaping tobacco or marijuana products

More Resources

• CDC Safety Guidelines: Wildfires and Wildfire Smoke
• CDC Wildfire Smoke Fact Sheet
• California Air Resources Board: Smoke Ready California
• Environmental Health Impacts of Wildfires