Depending on atmospheric conditions, fires that burn very hot can “inject” their smoke high into the atmosphere, where it’s less likely to dissipate, and then travel long distances.
“So it impacts more downwind communities than, potentially, the immediate community,” Magzamen said. “The actual air quality in Philadelphia, due to the fires right now, is very bad because of that long-range transport.”
In fact, on Tuesday, the air quality in Philadelphia was much worse than in areas near the wildfires — including Los Angeles, San Francisco, and Portland — all of which registered from “Good” to “Moderate” on the air quality index.
A second potential reason that communities closer to wildfires may experience fewer health effects, Magzamen says, is that they’re taking more precautions.
“If you have a local fire, you’re not only aware of the fire, but you’re aware of the smoke. So you’ll take more actions to probably shelter in place because of the emergency response associated with the fire,” she said. “But this long-range transport, what we think is going on is people are just not as air quality aware because the fire is thousands of miles away.”
So what exactly is this pollution? According to Trevor Penning, who teaches at the University of Pennsylvania’s Perelman School of Medicine, and directs the Center of Excellence in Environmental Toxicology, the biggest threat from wildfire smoke is from what’s called particulate matter.
“Usually, when you do this kind of combustion, you generate what we call particulate matter, which is ranked by size,” Penning said. “And the most hazardous is fine, fine particulate matter, that is smaller than 2.5 microns, which is smaller than the width of a hair in the human body. So you can’t see it, although you breathe it.”
The matter, Penning said, is made up of a carbon core, which itself contains other hazardous materials called polycyclic aromatic hydrocarbons.
“And we know that PM2.5, which are these fine particles, make their way into the deep lung,” he said. “And as a result, can exacerbate underlying lung conditions such as asthma, chronic obstructive pulmonary disease. We also know that these compounds can also exacerbate underlying cardiovascular illness. And in addition, long term, they can, they can actually invoke lung cancer.”