Find out just how bad wildfire smoke has been in your area
Smoke from wildfires in Canada brought record-breaking air pollution to the United States this spring, creating dangerous air quality from Bismarck, N.D., to Denver and Detroit to New York City and Washington. Another wave of smoke in late June broke smoke pollution records from Wisconsin to Ohio.
According to a Washington Post analysis of smoke data through June 27 from Stanford University, nearly 300 air quality monitoring stations have reported all-time high pollution from wildfires.
Wildfires can occur year-round, but most large fires burn between June and October. For this time of year, “what’s maybe unusual is the size of the fires and how far the smoke traveled,” said Brett Palm, a scientist who specializes in atmospheric chemistry at the National Center for Atmospheric Research in Boulder, Colo. “For the smoke to be as dense as it was this far away, it has to be a large fire.”
[Why wildfire smoke is bad for your health]
Across North America, wildfires are burning more land at a higher intensity, a phenomenon that wildfire experts attribute to climate change. Studies show a clear correlation between the number of acres burned by wildfires and higher temperatures. Heat waves in May in Alberta dried out vegetation, creating conditions that make large wildfires more likely.
How bad was the wildfire smoke where you live?
Chicago-Naperville-Elgin, Ill./Ind./Wis.
To isolate the impact of smoke on air quality from other pollutants, researchers at Stanford University’s Environmental Change and Human Outcomes Lab analyzed air quality measurements from the Environmental Protection Agency’s more than 2,400 air monitoring stations. If a station recorded high levels of air pollution and satellite imagery showed smoke plumes near a sensor during that same time, researchers attributed anomalous pollution to smoke.
Smoke’s impact on air quality depends on the amount of smoke a fire produces, which affects the density and size of plumes. The larger the smoke plume, the farther the smoke can travel. In May, the wind blew smoke from fires in Canada’s western and central provinces southeast and along the Rocky Mountains.
Two thousand miles away from the wildfires in Alberta, Denver residents experienced over a week of smoky skies and air pollution alerts. Dense smoke traveled downwind and created a spike in small particulate matter until “a front came through and brought clean air out of the mountains,” said Palm. “You could see in Boulder, the smoke got flushed right out of the area and the air was clean.”
[Here's what to know about the Canadian wildfires affecting parts of the U.S.]
Small air particles, or PM2.5, are particulate matter small enough to travel beyond the barriers in the nose and enter the respiratory system and bloodstream. The particles can cause inflammation in the lungs, exacerbating symptoms for people with respiratory conditions, or dislodge plaque in arteries, increasing the risk of stroke.
In Bismarck, the daily average of PM2.5 rose to more than 200 micrograms per cubic meter — the area’s highest one-day average on record. When levels of small particulate matter are that high, otherwise healthy people with no underlying conditions can start experiencing more serious health impacts, according to the Environmental Protection Agency.
The smoke in Bismarck was so dense that it reduced visibility to a quarter of a mile.
“It came over the top of the building like a white, smoky cloud and just inundated us for a day and a half,” said Ryan Mills, an ambient air monitoring manager for the North Dakota Department of Environmental Quality. “I’ve lived here my whole life and never saw it that bad, that thick.”
A low-pressure system brought the smoke to the ground and condensed it, Mills said, which created high concentrations of PM2.5.
In May, cities including Chicago, Philadelphia and D.C. experienced lower levels of air pollution over a longer period of time.
Neelima Tummala, a clinical assistant professor of surgery at GW Medical Faculty Associates and co-director of the Climate Institute at George Washington University, said the early-season smoke along the East Coast caught her by surprise.
[How to protect yourself from wildfire smoke]
“It wasn’t on people’s minds,” Tummala said. “Right now, I’m thinking about how do I think about heat, getting my patients prepared for July and August, and all the sudden, I started seeing these things about wildfire smoke.”
Sometimes, smoke causes air to look hazy, but Tummala said air pollution is often invisible to the naked eye, which is why it is important to check local air quality measurements. “People don’t think about, ‘Oh, this is a day where the air quality is poor, I need to be more cognizant, maybe make sure I’m traveling with my asthma inhaler.’”
Marshall Burke, an associate professor at Stanford University’s Doerr School of Sustainability who researches smoke pollution, said there is no “safe” level of small particulate matter or wildfire smoke exposure.
“We see impacts basically starting at zero,” Burke said. “The overall story is that more is bad.”
Smoke-filled air is particularly dangerous for people with underlying respiratory conditions and some studies suggest that fine particulate matter from wildfires is more harmful than air pollution from other sources. Increased levels of wildfire smoke in recent years are slowing or reversing clean air progress in states across the country, according to Stanford research.
When the air quality is poor, Tummala recommends wearing an N95 mask outside and limiting smoke exposure for pets. And while it’s important to limit exposure to smoke, “do I also want people to be outdoors exercising and doing good things for their mental and physical health? Yes,” she said. The most important thing is for people to listen to their bodies, because “everyone has slightly different responses to environmental irritants.”