Wildfire smoke caused 750 coronavirus-related deaths and 19,700 positive COVID-19 cases in western America last year, a study reveals.

Between March and December 2020, thousands of people living in California, Washington and Oregon were exposed to more fine particulate air pollution (PM2.5), often produced by wildfire smoke.

Researchers from Harvard T.H. Chan School of Public Health have found that increased amounts of PM2.5 pollution triggered extra coronavirus cases and deaths in western America.

Lead author, Professor Francesca Dominici said: “The year 2020 brought unimaginable challenges in public health, with the convergence of the COVID-19 pandemic and wildfires across the western United States.

“In this study we are providing evidence that climate change, which increases the frequency and the intensity of wildfires, and the pandemic are a disastrous combination.”

PM2.5 pollution is often associated with the most severe health complications, such as chronic obstructive pulmonary diseases (COPD), early death and asthma.

However, more recently it has been known to increase COVID-19 cases and deaths, the study reports.

The team of academics created a numerical model to measure how many coronavirus cases and deaths were caused by wildfire smoke in 92 counties across California, Washington and Oregon.

They compared the daily coronavirus data with PM2.5 pollution levels and the number of extreme wildfire days.

According to the results, the individuals who were exposed to high levels of PM2.5 pollution were more likely to be infected with COVID-19 compared to those who were not exposed.

They found that a 10 µg/m3 rise in PM2.5 would cause an 11.7% increase in coronavirus cases and nearly a nine percent increase in COVID-19 deaths.

Their findings also show that PM2.5 pollution was considerably higher when wildfires were larger, with some areas being exposed to a ‘hazardous’ amount of PM2.5, the U.S. Environmental Protection Agency reports.

Sonoma and Whitman were the counties with highest amount of wildfire-caused COVID-19 cases, with PM2.5 levels rising around 70%.

Meanwhile, Calaveras and San Bernardino were the counties with the highest amount of wild-fire caused COVID-19 deaths, with PM2.5 levels increasing around 60%.

“Climate change will likely bring warmer and drier conditions to the West, providing more fuel for fires to consume and further enhancing fire activity,” said Professor Dominici.

She added: “This study provides policymakers with key information regarding how the effects of one global crisis can have cascading effects on concurrent global crises – in this case, the COVID-19 pandemic.”

The entire research study can now be accessed in the journal ‘Science Advances’.

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