A significant portion of the U.S. is currently enveloped in smoke due to wildfires raging across Canada, which have spread air pollution as far as the Midwest and the Atlantic Coast. At the time of writing, Chicago, Detroit, and Washington, D.C., rank among the cities with the worst air quality globally.
The smoke poses severe health risks. Even smoke from distant wildfires can be hazardous to human health, potentially more so than other types of air pollution.
A 2021 study by researchers examining respiratory hospitalizations in southern California found that exposure to wildfire smoke particulates is about 10 times more harmful than exposure to other similar-sized particulate matter, specifically those smaller than 2.5 microns, which can enter the bloodstream. Researchers are uncertain whether this increased danger is due to the smoke’s unique chemical makeup, burning process, or another factor.
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A February study estimated that between 2006 and 2020, wildfire smoke was responsible for over 24,000 deaths annually in the U.S. The authors noted there was “no evidence of a ‘safe’ threshold” for exposure to wildfire smoke, with any exposure linked to an increase in all-cause mortality.
As smoke travels long distances, it can react with sunlight and urban pollutants to form ozone, a key component of smog. A study published in June in Science estimated that deaths due to ozone from wildfires have risen by more than 300 annually on average since 2013.
There is some evidence suggesting that wildfire smoke, like general air pollution, can affect mental health. As Scientific American reported in 2023, exposure to smog and other toxic air has been associated with lower test scores in children and increased stress and depression rates. However, these studies are limited and the specific impact of wildfire smoke on the brain remains uncertain.
It is evident that climate change is making wildfires more frequent and deadlier. Droughts and heat waves are becoming more common and intense, leading to an increased amount of dry vegetation that can ignite.
Despite the dangers posed by wildfire smoke, there are steps you can take to protect yourself. The U.S. Environmental Protection Agency advises staying indoors according to local advisories, keeping windows and doors closed, and using an indoor air filter if possible.
According to the U.S. Centers for Disease Control and Prevention, individuals with conditions like asthma and heart disease, pregnant women, and children are at higher risk and should take extra precautions.
If you must go outside, the CDC recommends wearing an N95 mask or P100 respirator for the best protection. Avoid outdoor exercise—its implications for this weekend’s World Cup final are yet to be determined.
Experts also suggest checking the Air Quality Index (AQI) in your area to assess local air conditions. Here’s a helpful guide on reading the AQI.
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