“Fine particulate matter air pollution can be an additional vehicle for spreading the virus even faster,” Francesca Dominici, co-author of the study and professor of biostatistics, population and data science at Harvard T.H. Chan School of Public Health, told CNN. “Considering that we are seeing an increased risk of cases from the Delta [variant] and we already have the wildfires, that’s going to be concerning.”
Dr. Albert Rizzo, chief medical officer at the American Lung Association, who was not involved in the new study, said that air pollution from wildfire smoke is likely causing inflammation in the lungs.
“The particulate matter is what leads the airways to be a very fertile ground for uninvited infection like the Covid virus to get into our airway,” Rizzo told CNN. “The immune system is only geared up to try to fight the effects of a particulate matter and now it has a virus that it has to trigger against as well.”
It’s a dangerous combination, Dominici said. “Right now, considering that we are seeing an increase in risks and cases due to the Delta variant, and we’re already getting wildfires, that’s going to be concerning,” she added.
The Harvard study looked at 92 counties in California, Oregon, and Washington impacted by wildfire in 2020. Using satellite images for the fires and public data on Covid-19 cases and deaths in the three Western states, researchers found that in the majority of the counties they studied, there was strong evidence that the more smoke and soot there was, the more there were cases and deaths from Covid. If PM 2.5 levels stayed higher for 28 days in a row, cases rose by nearly 12% and deaths by more than 8%.
“This is a very important study,” Donghai Liang, professor of environmental health at Emory University, who was not involved in the study, told CNN. “This is among those first studies that really report the link between particulate matter coming out of the 2020 wildfires in the United States and how they contribute to the exacerbation on Covid-19 cases and deaths.”
“Even without Covid, we’ve been concerned that climate change that leads to hotter environments, and droughts, is fodder for wildfires to occur,” Rizzo said “Then you add the wildfire ash and soot to the air quality, it does make respiratory issues much more likely to occur.”
“When you have a [wildfire] episode, we will see a huge increase in hospitalization for respiratory conditions or cardiovascular conditions — and that’s mostly the smoke, which is constituted mostly by PM 2.5,” Benmarhnia said.
“Kids inhale way more air than us, and their respiratory system is still being developed,” he said. “So they’re way more vulnerable than adults and it could be a very dangerous situation.”
It’s not just the toxicity of wildfire smoke, but also what the fire burns. Once the fire reaches a community and chars houses, it burns materials such as plastic that contain hazardous chemicals. But unlike the smoke, Benmarhnia said, the toxic emissions are not transported as far away, making it a problem for local communities.
As wildfires intensify, Dominici says she hopes that the study will push more people to act on environmental justice for communities most impacted and also the climate crisis at large.
“I hope that by showing how catastrophic the combination of wildfires and Covid-19 is, this will be an additional piece of evidence for increasing the emergency of combating climate change,” Dominici said.