As dozens of wildfires continue to rage in the Western United States, smoke from the blazes has wafted over much of the country, creating hazy skies and prompting air-quality warnings as far east as D.C., New York and North Carolina.
"This is peak fire season," said Grant Lipman, a clinical professor of emergency medicine at Stanford University and founder of the GOES Health app. The smoke from these "horrendous fires" can influence people's health locally, regionally and nationally, he added. "It gets into the eyes, the nose, the mouth - and it affects different people in different ways."
Here's what you need to know about the health risks of inhaling wildfire smoke and how to stay safe on poor-air-quality days.
- What are the health risks and symptoms of smoke exposure?
Wildfire smoke contains dangerous pollutants that include hazardous gases and particulate matter - solid particles and liquid droplets that are produced when wildfires burn through buildings, trees and other materials. While some particulate matter can be easily seen in the form of soot, smoke also carries smaller, invisible particles.
Cora Sack, a pulmonologist at the University of Washington, said health experts are especially worried about this smaller particulate matter, known as PM 2.5, as these minuscule particles can bypass the defense mechanisms of the upper airway and cause damage deep within the lungs. Some of the smallest particles may even be able to pass into the bloodstream and travel to other organs, she said. Sack added that studies have shown that extreme exposure to wildfire smoke has been associated with heart and lung problems.
The effects of smoke inhalation can vary from symptoms more akin to those of allergies - such as stinging eyes, a scratchy throat and a runny nose - to coughing, wheezing and shortness of breath, according to the Centers for Disease Control and Prevention.
"Your lungs don't want to inhale this, and so your lungs are going to do whatever is possible to keep the particulate matter - toxins that you're inhaling - out of your lungs," said pulmonologist Panagis Galiatsatos, an assistant professor at Johns Hopkins School of Medicine. Coughing and wheezing, for instance, occur as the body tries to make airways smaller to keep those particles from getting into the lungs.
People who experience symptoms should reach out to their primary care physician, and those with preexisting conditions should contact the specialist managing their care, such as a cardiologist or pulmonologist. "But if you feel breathless - like you're really struggling to catch your breath - I would strongly encourage going to an emergency room" and telling medical professionals you're having trouble breathing, Galiatsatos said.
- Who is more vulnerable to smoke exposure?
Anyone, including generally healthy people, can be negatively affected by wildfire smoke, experts said. But individuals with chronic lung diseases - such as asthma, emphysema and chronic obstructive pulmonary disease - and with preexisting heart conditions are more vulnerable; for them, even short-term exposure can cause serious health consequences that may require emergency care. There is some evidence suggesting that wildfire smoke is associated with an increased risk of cardiovascular events, including heart attacks and strokes, as well as an exacerbation of symptoms of heart failure.
Aside from people with lung and heart conditions, the elderly, young children and infants, and pregnant women are among those at the greatest risk. People who currently have or who are recovering from covid-19, the disease caused by the novel coronavirus, might also be more vulnerable to the health effects of inhaling wildfire smoke because they may have compromised lung and/or heart function, according to the CDC. Additionally, the smoke exposure can make a person more prone to lung infections, including covid, the CDC said.
- When should I be concerned about air quality?
Pay attention to warnings from the National Weather Service and local public health agencies, and make sure you're monitoring the air quality in your area, experts said. The air-quality index, or AQI, is an important guide "that tells us whether the air is good or bad," said Linsey Marr, a professor of civil and environmental engineering at Virginia Tech. "A number under 100 is good. A number over 100 is bad."
Websites such as the EPA's AirNow.gov provide a color-coded index explaining which levels may be hazardous and how much outdoor activity you should engage in. Green, which denotes when air pollution poses little or no risk, is associated with AQI values between 0 and 50. Once that number reaches the orange zone, 101 to 150, people who are sensitive to poor air quality may experience health effects. Red (151 to 200) means the air is unhealthy for everyone.
The worse the air quality is, the less time you should be outside doing strenuous activities, such as exercising, Marr said. "This is not the best time to go out for a two-hour walk, either."
- Will a mask help protect me against smoke and poor air quality?
Yes, but the type of face covering matters, said Chris Cappa, an environmental engineer and professor at the University of California at Davis. "Really, it becomes now quite important to have a higher-quality mask." That's because of the size of the dangerous particles found in wildfire smoke and other pollution.
"The particles that we're most worried about in the covid context tend to be quite a bit bigger than those that we're concerned about for things like wildfires, and so masks, generally speaking, are going to have lower efficiency for wildfire particles than they will for the covid-related particles," Cappa said. Cloth masks, especially, do not provide much protection from smoke.
Experts said good-quality masks, such as N95s, can help reduce smoke exposure when used correctly - tightly fitted to the face and covering the nose and mouth. But Lipman noted that N95s and similar respirators don't protect against the toxic chemicals that may be released into the air during wildfires. That's why, he said, on poorer air quality days "it's best just to stay inside."
- When should I wear a mask, and how do I take care of it?
If you have to be outdoors, consider the following factors when deciding whether to mask up: How is the air quality? Are you at increased risk of being affected? How long are you going to be outside? What will you be doing? "In general, I'd say the longer that you're going to spend outside, the more useful it would be to wear a high-efficiency mask," Cappa said.
For example, if air-quality levels are in the orange range, a vulnerable individual who plans to be outside for an extended length of time should don a mask.
Keep an eye on the state of your mask. Unlike cloth masks, respirators can't be washed. "If it becomes visibly soiled, like if you start noticing it getting brownish, then it's time to replace it," Marr said.
- What else can I do to protect myself?
Stay inside with the windows and doors shut, and take steps to purify the air in your space, experts said. If you're in your car, the air should be set to recirculate, Cappa said.
Similarly, you can recirculate the air in your home through a heating, ventilation and air conditioning (HVAC) system with good quality air filters. The higher a filter's rating, the more particles it will remove from the air, Marr said, but it's important to find a filter that's compatible with your HVAC system. Cappa recommended a filter with a MERV rating of 13.
It may also be helpful to run a portable air purifier indoors, the experts said. Make sure you use a HEPA air purifier that is the appropriate size for the space.
For those who do not have access to air conditioning or an air purifier, you can make your own purifier using a box fan and an air filter, but the CDC notes that those DIY units should never be left unattended.
Because wildfires often coincide with hot temperatures, people without air conditioning should consider seeking out an alternative place to be, such as cleaner air shelters or cooling centers.
If you have any preexisting conditions, experts recommend working with your doctor to formulate a plan and learn which symptoms to look for if your health begins to worsen. Lipman suggested keeping prescription medicines and inhalers handy if you need them. For milder symptoms of smoke exposure, consider buying over-the-counter eye lubricants or nasal sprays, he said.
"All that's going to make you feel a lot better and just being prepared will go a long way."
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The Washington Post's Sarah Kaplan contributed to this report.