‘Disastrous combination’: A Harvard study links wildfire smoke with worsened COVID-19 cases

Raging wildfires made the COVID-19 pandemic worse in the U.S. last year, and could be making it worse in parts of Canada right now, according to a Harvard study that came out last week.

The study, by lead author Francesca Dominici and a team of researchers at Harvard T.H. Chan School of Public Health, found that in 92 counties in California, Oregon and Washington in 2020 there were more COVID-19 cases and deaths when wildfire smoke was present than at times when it was not.

The study comes as COVID-19 case numbers in the interior of B.C. have been rising over the last several weeks — which is battling intense wildfires this year and the more transmissible Delta variant.

Dominici has called the overlapping crises of wildfires and the COVID-19 pandemic a “disastrous combination.”

Controlling for factors such as social distancing and population size, the researchers attributed 19,700 COVID-19 cases and 750 COVID-19 deaths to worsening effects from exposure to wildfire smoke.

In an interview with the Star Tuesday, Dominici said the team examined outcomes in the same areas over time, and adjusted for factors such as temperature, mobility and seasonal trends. As a result, they believe their findings apply any place exposed to wildfire smoke — including B.C.

“We were able to calculate the excess number of deaths and cases that could be directly attributable to these events,” she said. “In order for us to misattribute the impact of COVID-19 from the wildfires to something else, the something else would need to occur simultaneously to the wildfires.”

Dominici said she plans to continue the study using 2021 data of counties impacted by wildfire, which will tease out the impact of vaccines, as well as more transmissible variants.

The study paints a grim picture for parts of Canada that have been laden with smoke for the last six weeks, during fire season.

That includes the Central Okanagan, which is currently experiencing some of the highest COVID-19 case counts since the beginning of the pandemic, and regular waves of smoke from wildfires burning in the region.

Representatives from Interior Health, the health authority where the Central Okanagan is located, were not available to comment, but a spokesperson for B.C.’s ministry of health said the province does expect wildfire smoke to contribute to “some increase in COVID-19 transmission and severity.”

Marielle Tounsi added that’s not the only factor in the increased case numbers. There’s also the fact some people in the area are not yet fully vaccinated, and the increased threat posed by the Delta variant.

“There are still areas where there are larger pockets of unvaccinated people and this is where the virus tends to spread faster, especially the more transmissible Delta variant as we are seeing in the Central Okanagan,” Tounsi said.

Dominici agreed vaccination is especially key in areas with exposure to wildfire smoke.

“Counties that are susceptible to wildfires, I think that means there is an even more urgent need to vaccinate everybody there,” she said.

She also said employers and governments should do whatever they can to provide opportunities for people who work outside or live in conditions without air filters to come inside to safer spaces during wildfire season.

Due to climate change increasing the frequency and severity of fires, Dominici said, it’s something that susceptible regions can and should plan for.

“That’s something that should be done regardless of the COVID-19 pandemic, but COVID-19 places greater urgency and priority on it.”

TORONTO STAR