2023-06-09 06:15:00
As the thick layers of smoke from hundreds of canadian wildfires they descended on a great swath of USA This week, millions of people were urged to stay indoors, use HEPA filters, and only go out wearing high-quality face protection. Wildfire smoke, a seasonal hazard in some parts of the US, had become a problem for everyone almost overnight.
“It is a risk to our health”says Christine Wiedinmyer, associate director of science at the University of Colorado Boulder’s Cooperative Institute for Research in Environmental Sciences. “That’s all, from impact on the respiratory system, such as asthma, to the cardiovascular. There has been evidence that newborns born to women who are exposed to wildfire smoke during pregnancy have statistically lower birth rates.”
In many North American cities, some level of air pollution is routine, whether from fossil fuels, vehicle emissions, natural gas used for heating, or fumes from chemical production. But smoke from wildfires is particularly bad for humans.and that has to do with both the size of the particles involved and their composition.
Smoke is made up of “very small particles”
“Smoke from wildfires, especially smoke that has traveled a long way, is made up of very small particles”says Luke Montrose, an assistant professor and environmental toxicologist at Colorado State. “That’s what gives it the ability to be transient.”
Because the particles in wildfire smoke are tiny—much, much smaller than the smallest grain of sand—they have little trouble getting through the barriers our bodies have set up to keep pollutants out. Smoke particles can pass through the hairs in the nose and the mucous membranes that line the upper respiratory tract.
The smallest particles known as PM2.5can even cross the mucous membrane and reach the lower respiratory tract. That airway’s job is to “transfer oxygen across the blood barrier to the lung,” Montrose said, making this type of contamination particularly devastating for people who already have underlying lung conditions such as asthma or COPD. Even people with healthy lungs effectively get less oxygen, and those impacts aren’t always indicated by an overt symptom like a cough.
“People who may not be sensitive often have other symptoms like lethargy”Montrose said. “They may just feel bad, groggy, or have no energy. And that can be attributed to the lack of oxygen reaching the body.”
It is oxygen deficit It is also the reason people who are faced with poor air quality, especially outdoors, are discouraged from exercising. More activity means heavier, faster breathing, which brings more particles into the body and pushes them deeper into the lungs, ironically inhibiting the body’s ability to absorb oxygen when it is most needed. Impacts can also be long lasting. A 2020 study looked at a community in Montana that was exposed to wildfire smoke for more than a month; a year later, the residents were still suffering from decreased lung function.
“Potentially Toxic” Compounds in Smoke Resulting from Forest Fires
Smoke from forest fires also contains thousands of compounds, some of them potentially toxicsuch as volatile organic compounds, hydrocarbons and nitrogen oxides. A 2022 study published in The Lancet Planetary Health journal that looked at the effects of wildfire smoke on Canadians found that people who lived within 30 miles of a wildfire had a 4.9% increased risk of cancer. lung cancer and a 10% higher risk of brain cancer than unexposed populations.
The Dangers of Wildfire Smoke neither do they dissipate as it travels: Smoke released into the atmosphere becomes “aged” and more toxic over time. A 2020 study found that smoke samples taken more than five hours following their release from a fire were twice as toxic as when first released; following further aging in a laboratory, they were four times as toxic.
The smoke that traveled “had time to interact with the chemicals in the air, had time to interact with the sun,” Montrose says.
This week’s fires are just the beginning of what might be a smoky summer in North America, and a kind of new normal thanks to climate change. “The situation gets progressively worse, in terms of the severity of the fires, the length of the fire season, and the amount of smoke that has been released into the air,” says Wiedinmyer of the University of Colorado Boulder. “But there are ways to protect yourself. Stay inside, turn on your air conditioner when there is smoke, wear a mask outside [y] avoid exercising so as not to inhale these particles in the long term.”
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