Smoke caused by more than 200 out-of-control wildfires in Canada is producing unhealthy and even hazardous levels of air pollution throughout North America.
The smoke is spreading throughout much of the United States, especially the Northeast, Mid-Atlantic, Midwest, and parts of the Southeast. The National Weather Service has described parts of the country as looking like Mars, shrouded in an orange haze that blocks the sunlight and sends temperatures to unexpected lows.
Areas in the northern United States have been most dramatically affected, with New York City briefly ranked by IQAir.com as the most polluted major city in the world and Detroit in the No. 2 spot. “But the smoke and associated pollutants from fires in Northern Quebec are impacting as far south as Charlotte, North Carolina, and even farther because of the wind patterns,” says Rebecca Saari, PhD, assistant professor of civil and environmental engineering at the University of Waterloo in Ontario, Canada. “So you’re seeing air quality at unhealthy levels in many areas.”
Wildfires not only leave a trail of physical destruction in their immediate path, they also create a wave of health problems as harmful particulate matter and toxic gasses are carried through the air.
People exposed to wildfire smoke may experience everything from minor issues like stinging eyes, scratchy throats, and headaches to more severe reactions such as difficulty breathing and heart attacks.
“Wildfires are the largest environmental health risk factor contributing to premature deaths worldwide,” says Dr. Saari. In a recent study, researchers at the Massachusetts Institute of Technology in Cambridge estimated that smoke from human-ignited fires was responsible for the premature deaths of 20,000 Americans in 2018 alone.
Unfortunately, the fires may not be ending any time soon. The Canadian government is predicting continued higher-than-normal fire activity across most of the country throughout the 2023 wildfire season due to “ongoing drought and long-range forecasts for warm temperatures.” These conditions are likely due to climate change, experts believe.
With this outlook in mind, here’s what you need to know about how wildfire smoke can harm your health — even if you’re living thousands of miles from the flames — and how to protect yourself.
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Ways Wildfire Smoke Can Make You Sick
The U.S. National Weather Service notes that anyone can feel sick from exposure to air pollutants caused by wildfires. Bad air quality can lead to:
- Headaches
- Irritated eyes and sinuses
- Runny nose
- Increased coughing and scratchy throat
- Fatigue
- Chest tightness
“If you feel extreme shortness of breath or chest pain that’s concerning, you will want to get to an emergency room or call 911,” says Timothy Daum, MD, a pulmonologist with University of Michigan Health–West in the city of Wyoming.
Who Is at Highest Risk From Wildfire Smoke?
The Centers for Disease Control and Prevention (CDC) warns that adults over 65, children (with developing lungs), and pregnant individuals are most susceptible to wildfire smoke.
Those who already have underlying lung issues — such as chronic obstructive pulmonary disease (COPD), asthma, and bronchitis — face a higher risk of breathing difficulties. “Smoke adds insult to already injured lungs,” says Purvi Parikh, MD, an allergist and immunologist with NYU Langone Health in New York City and a spokesperson for the Allergy and Asthma Network.
As Dr. Daum points out, pollutants caused by wildfire smoke can also aggravate chronic cardiovascular issues. People with heart disease should be on the alert for signs of heart attack, stroke, and arrhythmia (irregular heartbeat). “When these small particulate matter get into a person, they set up inflammation and adverse consequences throughout the body,” says Daum.
Air pollution can also throw off your immune system, making you more susceptible to any type of respiratory virus, including the flu, RSV, and COVID-19. Research from Harvard University found that even a slight rise in particulate matter in the air was linked with a 15 percent increase in the COVID-19 death rate.
While the long-term effects of wildfire smoke are not certain, Cancer Research UK considers exposure to air pollution to be a risk factor for lung cancer.
“Damage to heart, vasculature, and lungs can be permanent, and it can be fatal,” says Otis Brawley, MD, a professor of oncology and epidemiology at Johns Hopkins University in Baltimore.
Why Wildfire Smoke Is So Dangerous
While all the pollutants that wildfire smoke releases can harm your health, the EPA says that fine particles from wildfire smoke pose the biggest threat. These particles are measured as PM2.5, atmospheric particulate matter that has a diameter of less than 2.5 micrometers, according to an article published in the Journal of Thoracic Disease.
These minute pollutants, which are just 3 percent of the diameter of a human hair, are particularly hazardous. The body can filter out many coarser particles, but PM2.5 can penetrate deep into the lungs and impair their function.
The EPA considers it safe to breathe in PM2.5 levels that don’t go over a concentration of 35 micrograms per cubic meter of air (mcg/m3) within a day, as long as the yearly daily average comes out to 12 mcg/m3 or less.
Mary Prunicki, MD, director of air pollution and health research at Stanford University in California, warns that it doesn’t take much of a rise in PM2.5 to ignite health problems.
“With just a 10-unit increase in PM2.5, you’ll see an uptick in emergency room visits and hospital admissions for heart attacks, strokes, arrhythmias, and severe breathing problems related to asthma, COPD, or bronchitis,” she says. “When the level reaches 200 it’s like smoking almost 9 or 10 cigarettes a day, and that’s for everyone — babies and older people included.”
Dr. Prunicki believes we will see increased PM2.5 levels more frequently. “With climate change, wildfires are happening so much more frequently and more intensely,” she says. “More extreme weather also means more winds, so it doesn’t surprise me that even a place as far from Canada as New York City is getting air pollution like this.”
How to Protect Yourself From Wildfire Smoke
When air quality veers into the danger zone, take these steps to protect yourself:
- Avoid going outside. One of the easiest actions to minimize smoky air intake is to stay indoors. The CDC instructs people to keep windows and doors shut, and run an air-conditioner, but keep the fresh-air intake closed and the filter clean to prevent outdoor smoke from getting inside. Those without air-conditioning may want to seek out an air-conditioned community center.
- Keep exercise indoors and to a minimum. Physical activity increases breathing and heart rates, so when air quality levels go into the red, exercise inside and at a moderate (rather than high-intensity) pace. “Overexertion should be avoided,” says Dr. Brawley.
- Wear an N95 mask. Daum advises wearing an N95 mask that fits snugly to the face if outdoors for a long time. “A regular cloth mask or regular surgical mask probably won’t do much. An N95 probably won’t filter out everything, but it will help.”
- Consider using an air purifier. Tests by Consumer Reports of air purifiers with HEPA filters show that they can help get rid of harmful particulates. The best air purifiers can reduce particle concentrations by as much as 85 percent. They range in price from $50 to more than $1,000.
Online Air Quality Alerts Can Help You Assess Your Risk
When huge fires flare up and blanket vast regions, it’s important to check air quality alerts (on sites such as IQAir and the EPA’s AirNow), which measure major pollutants, such as ground level particulate matter, carbon monoxide, ozone, and sulfur dioxide.
A very unhealthy measure on the air quality index (AQI), per AirNow, is between 201 and 300, and anything above that is considered “hazardous.” New York City’s AQI went above 400 in early June, and Prunicki cautions that some areas near to fires have topped 500 on the AQI. Even levels as low as 51 to 200 can result in serious health complications for more sensitive groups.
