On July 17, smoke from wildfires in Ontario, Canada, reached Fairfax County, resulting in dangerously low air quality. During these low-air-quality periods, people are advised to avoid going outdoors and to minimize physical exertion.
Typically, the smoke would be carried east to the ocean, but an abnormal wind pattern took it south.
Daniel Tong, associate professor of Atmospheric Chemistry and Aerosols at George Mason University, said this “formed a river of very thick smoke” that went over the Midwestern U.S. to the Washington, D.C., area.
Further degradation of air quality in the area depends on two main factors, according to Tong: how long the wildfires burn, and whether new ones start and whether the wind blows the smoke to the east or to the south again.
As of July 18, models showed air quality would improve within days, but Tong said, “You do not know if the model is perfectly right or not.”
Wildfire smoke is very dangerous for people to inhale. According to Dr. Eric Libre, a pulmonary physician at Inova, around 80% of wildfire smoke consists of particles 2.5 micrometers or smaller in diameter.
These particles are referred to as PM2.5, and are especially dangerous for people to breathe. Dr. Tong said, “Because it’s so small, it can get very deep into your lungs, and then most of this will never come out.”
At the height of the smoke in the area, the PM2.5 concentration was 200 micrograms per cubic meter.
“This is at least 10 times more [concentration] … you are putting a lot of particles into your lungs. Ten times more than normal time,” Tong said.
PM2.5 particles are especially dangerous because of their small size. “These fine particles can easily get inhaled,” said Libre. “They don’t get stuck in our nose, in our throat, and they go all the way down into the smallest parts of our lungs.”
These small particles can cause discomfort for people, such as “coughing, wheezing, chest pain,” according to Tong.
“It’s generating this stress on your respiratory system that has an impact on your health from lack of sleep … and all kinds of problems,” Tong continued.
Libre said that certain groups are particularly vulnerable to harm from the smoke, including children under 5, adults over 65 and people with pre-existing cardiopulmonary conditions.
Additionally, pregnant women are at risk from low air quality.
“Studies have shown that significant exposure to air pollution can increase the risk of pre-term birth and low birth weight,” Libre said.
People who work outdoors because of the nature of their job are also at risk because they have more exposure to airborne particles.
To keep safe, both Tong and Libre advised people to stay indoors.
“On those days where it’s code red … people should be aware of staying out of the outside air as much as possible, trying to be inside where the air is filtered,” Libre said.
If going outside is necessary, wearing an N95 or P100 mask can help diminish the effects of the air pollution. Libre warns that “the regular paper cloth masks are probably not very effective because they may not stop these ultra-fine particles.
High-efficiency masks are needed because they can trap particles 2.5 micrometers or smaller and fit more tightly to the wearer’s face. Libre said this makes them much more effective at protecting against high PM2.5 concentrations.
While air quality in the area is being affected by the Canadian wildfires, Libre advises people to pay attention to the air quality index (AQI) categories.
Libre also said people should pay attention to any symptoms they experience.
“Say you’re outside, you’re feeling short of breath, you’re coughing more … Those are all symptoms that you should get out of the outside air,” he said.
If the symptoms do not dissipate after going indoors, Libre encourages getting professional help.
“Sometimes, that can be the first manifestation that we see that somebody actually has asthma,” he said.
Libre also advised people with asthma or chronic obstructive pulmonary disease (COPD) to have their rescue inhaler with them while at dangerous AQI levels.