The Best Ways to Protect Yourself From Wildfire Smoke and Ash

The Los Angeles wildfires have killed at least two dozen people and decimated thousands of structures. Yet even in areas that aren’t burning, plumes of smoke remain a serious and ongoing public health threat—especially as the region braces for dangerous winds that could fuel the spread of ash and smoke.

“Certainly air pollution problems are nothing new for people who live in Los Angeles and Southern California, but this is a little bit different,” says Dr. Jeremy A. Falk, a pulmonologist and associate professor of medicine at Cedars-Sinai in Los Angeles. “What we’re really worried about is the PM2.5 levels,” or the fine particles in wildfire smoke, which have a diameter of less than 2.5 micrometers. In order for particles to enter your lungs’ air sacs, he says, they have to be just the right size; if they’re too tiny, you’ll breathe them in and out without experiencing any problems, and if they’re too big, they’ll get stuck in your nose or mouth. PM2.5 particles, meanwhile, can settle deep in the lungs, causing a variety of health effects.

“If this was all organic smoke—meaning things like trees and vegetation that was burning—we’d have a general sense of what people were inhaling,” Falk says. “But with all the buildings and houses and plastics and chemicals, there’s all sorts of stuff in the air, and the particle sizes that are in that 2.5 range are the ones most likely causing most of the problems.”

Read More: What Wildfire Smoke Does to the Human Body

Over the short term, elevated PM2.5 exposure can cause a runny nose, coughing and wheezing, eye and throat irritation, and even bronchitis and pneumonia, Falk says. Research suggests high levels can increase the risk of heart attacks, strokes, and arrhythmias, while also raising blood pressure. Certain populations—including young children, the elderly, and people with preexisting heart and lung conditions—are most at risk, though anyone can be affected.

It’s too soon to say exactly how the winds forecast to hit Los Angeles will affect the situation. What kind of impact they have depends on their exact patterns. They could “help or hurt,” Falk says. “If most of this gets blown out to uninhabited areas or the ocean, it’s going to do less harm. But it’s certainly, unfortunately, been quite unpredictable.”

Here’s how experts advise people in affected areas to take steps to protect themselves.

Check your local air-quality report

Websites like AirNow.gov offer a real-time status update on the air quality in your neighborhood. Check the Air Quality Index first thing every morning, and again throughout the day, says Dr. John Belperio, interim chief and professor of medicine in the division of pulmonary, critical care, sleep medicine, clinical immunology and allergy at The David Geffen School of Medicine at UCLA. Levels can change rapidly, depending on how fires are progressing and what the weather is like, which is why it’s important to make yourself a repeat visitor.

Then adapt your behavior accordingly: If you’re in a green zone (under 50—and parts of LA have registered there at varying times over the past week), it’s generally OK to proceed with your day in normal fashion. Once the air quality level is over 101, however, people with underlying lung disease should take extra precautions and stay indoors as much as possible. “Once the levels start getting above 150”—as was the case in Central LA last week—“everyone can be affected,” he says. “Everybody can have a little bit more inflammation in their lungs.” In those cases, it’s best to rethink any outdoor activities—skip your outdoor bike ride or jog, for example, and hit your home gym instead.

One caveat: Falk doesn’t always blindly trust air-quality reports. “With these maps that are readily available on pretty reputable websites, you don’t necessarily know for sure what they’re measuring,” he says. So if you look outside and it seems really smoky, but you’re allegedly in a green zone, proceed cautiously. “Until the fires really die down, I would recommend continuing masking while you’re outside.”

Wear a specific type of face mask

Over the last four or five years, we’ve all become self-proclaimed mask experts. But it’s important to understand why the kind of mask you wear during a wildfire might be different from what you wore to protect yourself from COVID-19, Falk notes. “COVID spreads from person to person through respiratory droplets, and while you can’t see those droplets—they’re still microscopic—they’re much, much larger than the particles we’re talking about from smoke,” he says. “Because the [virus] particles are bigger, you could get away with using relatively unsophisticated masks. But for this, because the particles are so tiny, they’ll pass right through a cloth mask.” He recommends that people in LA wear a tight-fitting N95 or KN95 mask any time they go outside; P-100 respirators also work well and filter out 99.97% of airborne particles.

Make some changes inside your home

If you live in an area affected by wildfire smoke, keep your windows and doors shut, and seal any obvious cracks, Falk advises. It can also be helpful to keep your air conditioner on (or at least its fan)—though ideally, it won’t be the kind that brings in outdoor air. “You’re much better off recirculating air that’s already inside because it’s a lot cleaner,” he says. The same goes for your car AC. It’s also smart to change the filters in your air-conditioning system regularly, since they might be getting dirty from wildfire smoke.

Air filtration systems can elevate indoor air quality, too. “HEPA filters are great,” Falk says. “The higher the MERV rating, the better, because what that means is it’s basically filtering out smaller particles.” MERV—which stands for “minimum efficiency reporting value”—measures how well an air filter traps particles; the U.S.Environmental Protection Agency (EPA) recommends using MERV 13 filters to make sure you’re removing very small particles, like those in wildfire smoke.

Read More: ‘Completely Overwhelming’: L.A. Fire Victims Describe Their Devastating Losses

If you have an air purifier, turn it on, Belperio says. These machines vary greatly in quality, and “there’s not the greatest of data—it hasn’t been rigorously studied,” he adds. “But if you’re in a bad area, I think it can actually be somewhat helpful.” While the EPA doesn’t recommend specific brands of air purifiers, the American Lung Association suggests making sure yours is a mechanical air cleaner that filters out particles using HEPA filters; you should also check to see if it’s certified by the California Air Resources Board. Consider the size of the room where you’ll be using it, too: According to the American Lung Association, use a purifier with a clean air delivery rate (CADR) of up to 200 cubic feet per minute (CFM) for a small room, 200-300 CFM for a medium-sized room, and at least 300 CFM for a large room.

Don’t add extra chemicals to the mix

Avoid turning on your fireplace, burning a candle, or frying food during the wildfire crisis. All can release chemicals and contribute to air pollution, says Jun Wu, professor of environmental and occupational health at the UC Irvine Joe C. Wen School of Population and Public Health. “It’s already hard for us to clean out the air because of all the fires, and all these particles penetrating into the indoors,” she says. “Think about your lungs and your body as a system that can handle a certain amount of environmental stressors and insulating chemicals.” By generating additional air pollutants, you’ll be putting an even greater burden on your systems, she says, which can take a toll on health.

Clean off ash-covered surfaces with a damp mop

Sometimes during wildfires, ash—or particulate residue that remains or is deposited on the ground after a fire—might settle in a layer on even indoor surfaces. If there’s ash inside your home, wear an N-95 or P-100 mask while you’re cleaning up. It’s also a good idea to put on goggles, gloves, a long-sleeved shirt, and long pants, according to the South Coast Air Quality Management District (AQMD). That way, your skin won’t come into contact with ash.

Read More: What to Say to Someone Who Lost Everything in the California Wildfires

If you’re sweeping up ash inside your home, mist it with water first, and then use a damp cloth or mop to clean surfaces, Wu advises. Bag it up before throwing it away, the AQMD suggests. Avoid vacuums unless they have a HEPA filter. “Dry vacuum cleaning can actually rouse these particles,” Wu says. “Normally when you ‘dry’ clean your house, you would get a high amount of fine particle exposure around you, like with dust,” she says. “You’re creating a personal cloud of fine particle matter in your home.”

Shower liberally

If you live in close proximity to the fires and have to go outside, you could end up with particulate matter on your clothing and skin. “It can be secondary pollution,” Wu says. “It can be carried indoors and spread to others.” That’s why she suggests taking a shower as soon as you get back inside—and washing your dirty clothes. 

Go to the doctor when you need to

If you experience severe coughing, shortness of breath, chest pain, or heart palpitations, you should see a doctor. But it’s also important to pay attention to seemingly less dire symptoms. As everyone in California focuses on the fires, there’s a tendency to ignore other potential health ailments. “We’re in winter,” Belperio says. “There’s a lot of winter viruses. We’re seeing plenty of rhinovirus and influenza, and we’re still seeing some COVID. Don’t just think that this is all fire-related, and that you don’t have to do anything.” 

If you feel like something is off, call your doctor, he advises—they may tell you to put a mask on and come in, or set up a telehealth appointment you can join from home.