A Pacific Gas and Electric firefighter walks down a road as flames approach in Fairfield, California on August 19, 2020 (AFP / Josh Edelson)

CDC did not give contradictory advice on mask use for smoke, Covid-19

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Social media posts claim the US Centers for Disease Control and Prevention (CDC) contradicted itself by advising people to wear cloth masks against the novel coronavirus while also saying masks do not stop smoke inhalation during a wildfire. These claims are misleading; the agency explained that a mask is recommended to contain respiratory droplets, which are larger than smoke particles.  

The claims came after an August 30, 2020 CDC warning on Facebook said: “Cloth masks that are used to slow the spread of Covid-19 offer little protection against wildfire smoke. They do not catch small particles found in wildfire smoke that can harm your health.” 

Directly under the CDC’s post users began mocking the agency for making such a statement. 

Unprecedented wildfires have for weeks been ravaging the West Coast, and the health agency recommended, “Limit your time outside when it’s smoky,” while redirecting to a resource page on wildfires and Covid-19.

A screenshot of the CDC Facebook post, taken on September 29, 2020

Claims then started circulating with screenshots from the CDC’s Facebook post -- here, here and here -- and on Twitter and Instagram

A screenshot of a Facebook post taken on September 28, 2020

Taison Bell, critical care and infectious disease physician at the University of Virginia, told AFP that the social media commentators “are missing the point of why they should wear a mask in the first place.” 

He also added that only one mask, the N95 respirator, effectively fitters coronavirus particles.

“Surgical masks, cotton masks, are not designed to filter in that way. What it does is decrease the amount of respiratory droplets that go to the atmosphere, so that there is less of these droplets and particles that can cause contamination,” Bell said by phone. 

The CDC similarly pointed to masks’ benefits in blocking droplets that could spread the novel coronavirus, and stood by its original statement when contacted by AFP. The agency recommends cloth masks “as a simple barrier to help prevent respiratory droplets from traveling into the air and onto other people when the person wearing the mask coughs, sneezes, or talks.”

A spokesperson added that “CDC does not advise using cloth masks to protect against wildfire smoke because although they may help with larger particles and ash, they could still let the smallest and most harmful particles through. Instead, people should stay inside and avoid smoke as much as possible.”

Experts on climate, fires and weather patterns told AFP that the blazes in California, Oregon and Washington were down to multiple factors, but global warming has played a central role.

The California Department of Public Health recommends people stay inside as much as possible, but to wear an N95 respirator that can filter out smoke or ash particles when outside (AFP / Josh Edelson)

This year’s infernos have burned more than five million acres, killed dozens of people and forced hundreds of thousands from their homes.

The California Department of Public Health referred AFP to reports, written in collaboration with the CDC and the US Environmental Protection Agency, that corroborate the recommendations mentioned in the CDC Facebook post from August.

The department generally recommends people stay inside as much as possible. If they have to venture out, it recommends using an N95 respirator that can filter out smoke or ash particles. “Surgical masks and one-strap dust masks will not protect your lungs,” a 2018 EPA report warns

AFP Fact Check has debunked other examples of false or misleading information about the US wildfires, here, here and here