Thousands of extra COVID cases and deaths ‘caused by smoke from wildfires’

ATHENS, GREECE - AUGUST 17: Wildfire in a forested area near the village of Vilia in Athens, Greece on August 17, 2021. (Photo by Ayhan Mehmet/Anadolu Agency via Getty Images)
Wildfire near the village of Vilia in Athens, Greece on August 17, 2021. (Getty)

As wildfires grip the world again this summer, an American study has shown that pollution from the blazes is causing extra deaths from COVID-19.

Wildfires release fine particles which can affect people’s airways - and make more people catch COVID and die from it, according to the study.

Watch: 'The moment of crisis has come' - David Attenborough on climate change

The study shows that thousands of extra COVID cases and deaths in California, Oregon, and Washington between March and December 2020 may have been caused by fine particulate air pollution released in wildfire smoke.

Areas with high levels of smoke pollution from wildfires saw an increase of up to 65.9% in COVID deaths due to the fine particles which can affect airways.

Read more: A 1988 warning about climate change was mostly right

The Dixie Fire burns down a hillside towards Diamond Mountain Rd. near Taylorsville in Plumas County, Calif., on Friday, Aug. 13, 2021. (AP Photo/Noah Berger)
A wildfire in California in August. (AP)

The pollution (technically known as PM2.5 pollution) is linked to premature death, asthma, chronic obstructive pulmonary diseases (COPD), and other respiratory illnesses.

Lead author Professor Francesca Dominici of Harvard Chan School 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.”

In 2020, huge wildfires swept across the western US, including some of the largest ever in California and Washington.

The researchers looked at the connection between PM2.5 air concentrations from monitoring data, wildfire days from satellite data, and the number of COVID-19 cases and deaths in 92 counties, which represented 95% of the population across the three states.

Wildfires were linked to increased pollution which had an impact on COVID deaths. (AP)
Wildfires were linked to increased pollution which had an impact on COVID deaths. (AP)

Read more: Why economists worry that reversing climate change is hopeless

The study found that from 15 August to 15 October, 2020, when fire activity was greatest, daily levels of PM2.5 during wildfire days were significantly higher than on non-wildfire days.

On average across all counties, the study found that a daily increase of 10 µg/m3 in PM2.5 each day for 28 subsequent days was associated with an 11.7% increase in COVID-19 cases, and an 8.4% increase in COVID-19 deaths.

The biggest effects for the COVID-19 cases were in the counties of Sonoma, California, and Whitman, Washington, with a 65.3% and 71.6% increase, respectively.

The biggest effects for the COVID-19 deaths were in Calaveras, California, and San Bernardino, California, with a 52.8% and 65.9% increase, respectively.

Read more: Melting snow in Himalayas drives growth of green sea slime visible from space

Across the three states studied, the cumulative number of COVID-19 cases and deaths attributable to daily increases in PM2.5 from wildfires was, respectively, 19,700 and 750, the study found.

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

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

Watch: Hydrogen: what is it, and can it help tackle climate change?