For millions of people across the northeastern United States and Canada this week, the sun turned red, obscured in a haze of smoke from wildfires burning in Quebec and Ontario. Wildfires are typical in these regions, but this year is particularly intense. According to NASA's Earth Observatory, in an average year, less than a square mile of forest would be burned by now. But so far this year, over 600 square miles have been scorched.
With air quality declared a "very high risk for health" in cities like Toronto and Ottawa, tens of thousands of people have been evacuated across Canada. As the smoke has moved south to cities including Boston, New York, Detroit, Philadelphia, and Washington, D.C., it has impacted travel and caused some school districts to suspend outdoor activities. On Wednesday, June 7, the air quality index in and around New York City was the worst since the US Environmental Protection Agency (EPA) began recording measurements in 1999. The Massachusetts Department of Environmental Protection issued a statewide air quality alert that expired at midnight on June 7, but the worst air quality is expected to hit Toronto on Thursday, June 8, and smoke will continue to blow over parts of the US.
Say it isn't smoke… but yet here we still are. The highest concentrations of smoke should be dissipating through the morning hours and into the afternoon across the region. However late this evening, we anticipate the haze and smoke to become more dense. pic.twitter.com/QwouQYq4s7
- NWS Mount Holly (@NWS_MountHolly) June 8, 2023
As the smoke has moved south, it's forced many residents indoors or to wear masks when they're outdoors. National Weather Service Philadelphia/Mount Holly
How did the Wildfires Start?
Some of these fires were ignited from lightning, and some by humans, but they are stronger due to dry conditions caused by warming temperatures. Climate change creates hotter, drier conditions, leading to longer and more active fire seasons-and, unfortunately, there's no sign they're going to slow down anytime soon. As large fire events become more common, what can people do to protect themselves?
"When I see this level of smoke from wildfires, my first concern is how much worse and more common these events may become with climate change," says Jeff Geddes, a Boston University College of Arts & Sciences assistant professor of Earth and environment who studies air quality. Many communities in the western United States have been experiencing this for years, but "people who are not used to worrying about the air they breathe will need to start preparing themselves and educating themselves about how to protect their health," he says.
How Wildfires Affect our Health
When it comes to wildfire smoke, the exact composition depends on the properties of the vegetation, the temperature of the fire, and other environmental factors. "You can expect a mix of really nasty constituents like soot, carbon monoxide, and toxic hydrocarbons," Geddes says. Health experts and researchers worry the most about particles with a diameter of less than 2.5 micrometers, known as PM2.5, and often called particulate matter or fine particulate matter. These particles are potent in wildfire smoke, and small enough to get past the body's natural defenses, such as the tiny hairs in your nose, and settle in the lungs. Air quality alerts often warn residents to stay indoors when PM2.5 levels are above 100-the Air Quality Index, established by the EPA, runs from 0 to 500; the higher the number, the higher the level of pollutants like ground-level ozone, particulate matter, carbon monoxide, nitrogen dioxide, and sulfur dioxide.
"Many studies have shown the negative impacts of exposure to fine particulate matter from smoke," says Jennifer Stowell, a postdoctoral fellow at BU's School of Public Health who studies environmental health effects from wildfires. "Wildfire-specific fine particulate matter has been linked to clinical and emergency department visits for respiratory issues, including asthma, decreased lung function, chronic obstructive pulmonary disease, and others."
These effects are also thought to have a higher impact on vulnerable populations. For example, Stowell's research has found more respiratory disease impacts in children when compared with adults. She's working to delve deeper into the questions surrounding wildfire smoke exposure and pregnant women, who are also considered a vulnerable group.
"While predicting the future is difficult, I and others have shown potentially dramatic increases in adverse health impacts due to wildfire activity by the 2050s and beyond," she says.
The Environmental Effects of Wildfires
Wildfires not only impact human health and well-being, but they transform the very landscape that protects us from climate change: forests. Today's forests capture about 30 percent of all human-related CO2 emissions. But according to research from BU environmental Earth scientist Mark Friedl, fires in the world's northernmost forests can potentially hinder their ability to sequester as much carbon as previously expected, making efforts to reduce greenhouse gas emissions, like carbon and methane, all the more urgent.
"Most forests in Canada are adapted to fire-it's part of their natural cycle," says Friedl, a CAS professor of Earth and environment and the director of BU's Center for Remote Sensing. "Climate change, specifically warmer and drier conditions, is leading to more frequent and more intense fires, which release carbon to the atmosphere and reduce carbon stocks stored in these forests."
Boreal forests, like those in northern Canada, are a large and important part of the global climate system, and these changes can feed back into the climate system in complex ways that we don't fully understand, he says. "We should not forget that even though many of these forests are sparsely populated, they are home to a significant population of indigenous peoples whose lives and livelihoods can be seriously affected by wildfires," Friedl says.
And even though these fires are hundreds of miles away from Boston, we can feel and see the effects. To protect yourself from smoke in the short term, the easiest thing to do is to remain indoors, Geddes and other health experts say, and keep the windows shut until the air quality emergency is over. Running air-conditioning or air purifiers is also encouraged, Stowell says, but if you're unable to stay inside, your best bet is wearing an N95 mask with double straps that can filter smaller particles like PM2.5.
"The fact that we can all see this smoke, and recognize that we are breathing in this material, might hopefully raise the appropriate level of alarm," Geddes says.
