The claim: Face masks cannot protect against inhaling wildfire smoke particulates so they are also ineffective against COVID-19
West Coast states are experiencing some of the worst wildfires on record amid the most infectious global pandemic in a century. An epidemic of misinformation is also hurting efforts to combat the natural disasters.
An image shared on Facebook juxtaposes a statement about the average size of coronavirus and wildfire smoke particulates with a screen-grabbed CDC tweet that states cloth face masks do not protect against wildfire smoke. "They do not catch small particles found in wildfire smoke that can harm your health," the CDC states.
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There are red lines drawn between the numbers and the CDC statement to connect the two. The implication appears to be that face masks do not protect against either coronavirus or wildfire particulates, as viral particles are on average smaller - at "0.12-0.3 microns" - than smoke - "at 0.7-0.4 microns." USA TODAY reached out to the original poster of the image for comment.
The claim is misleading as it misinterprets both why cloth masks are ineffective against protecting people from the effects of wildfire smoke as well as why they are useful in slowing the spread of the coronavirus.
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Masks, respirators and wildfire smoke
The Centers for Disease Control and Prevention has emphasized that cloth masks are not effective at protecting people from inhaling wildfire smoke. The agency urges that people refrain from being outside and risking exposure to heavy particulates.
"Cloth masks that are used to slow the spread of COVID-19 by blocking respiratory droplets offer little protection against wildfire smoke," an agency blog entry reads. "They do not catch small, harmful particles in smoke that can harm your health."
This statement underscores a truth about cloth masks: They are less effective at stopping the inhalation of dangerous particles.
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However, the CDC notes that higher quality "N95 respirators do provide protection from wildfire smoke" but that "they might be in short supply as frontline health care workers use them during the pandemic."
The Environmental Protection Agency also states that "people who must be outside for extended periods of time" during fires "may benefit from using a tight-fitting N95 or P100 respirator to reduce their exposure."
This is because properly worn respirators are a strong enough filter to stop smoke particles from entering a person's lungs, where ash, smog and other compounds can inflict serious harm to the body.
For many people living near wildfires, the debris and smoke is inescapable. Air quality in many regions on the West Coast has reached toxic levels.
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"My advice to the public is that people should be sheltering in place as much as possible," said John Balmes, a professor of medicine at University of California, San Francisco. "Stay home with windows closed, ventilation turned to recirculate, and if possible, have a clean air room with a HEPA air purifying appliance."
This reality with wildfires is a different dynamic from the role that respirators and cloth masks can play in slowing the spread of the coronavirus.
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Cloth masks, coronavirus and wildfires
Cloth masks and other nonmedical grade face coverings are effective at slowing the spread of the coronavirus not because they are the best way to stop a person from inhaling infectious particles and droplets.
Rather, face coverings are widely mandated because they make it more difficult for infected people to spread the virus in the first place.
"Masks are recommended 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, talks, or raises their voice. This is called source control," the CDC states in its guidelines.
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SARS-CoV-2, the novel coronavirus that causes COVID-19, is mostly spread through droplets and other particulates, which people can share by coughing, sneezing, singing, talking or yelling.
While face coverings like cloth masks are only marginally effective at stopping all viral particles from being inhaled, they are more effective at stopping people from putting more particles into their environment.
This means that when large majorities of the public wear face masks, the aggregate effect can seriously slow the spread of a respiratory disease like COVID-19.
"COVID-19 can be spread by people who do not have symptoms and do not know that they are infected. That's why it's important for everyone to wear masks in public settings and practice social distancing," the CDC emphasizes.
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Scientists are still debating just how effective cloth masks are at protecting an individual person.
While the combined effect of slowing contagion is the true value of simple face coverings, researchers do believe that cloth masks provide some form of personal protection against coronavirus and are just uncertain how much.
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A complicated public messaging campaign
Face masks have been the subject of confusion and scrutiny during the coronavirus pandemic. In the USA, this has partly come from mixed messaging from government agencies like the CDC, as well as the Trump administration.
Public guidelines urging the wearing of face masks have evolved over the course of the pandemic. Health officials, aware of how most widely available masks don't provide the personal protection that medical grade respirators offer, were at first hesitant to encourage widespread mask-wearing.
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The CDC reversed messaging when it became apparent that Americans could make and wear enough cloth masks to slow the virus's spread.
The West Coast's wildfires are now making officials concerned that many won't be able to distinguish between symptoms from exposure to wildfire smoke and COVID-19.
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The CDC and state public health departments have issued guidelines for how to distinguish between the symptoms, measures to protect against wildfire smoke and coronavirus, and advise that people should support each other in this time of crisis.
"Some people most vulnerable to wildfire smoke, like those over 65 or with preexisting conditions, are also those most at risk for serious impacts from COVID-19. Check on your neighbors and make sure they know how to keep the air clean in their homes," a Medium post from the Washington Department of Health reads.
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Our ruling: Missing context
Cloth masks are not granular enough to protect against smoke and airborne particles from the wildfires gripping the Western USA, according to CDC guidelines. The CDC and other agencies still endorse masks for slowing the spread of COVID-19 because of their usefulness if widely adopted. N95 respirators and similar quality personal protective equipment protect against both wildfires smoke and coronavirus particles but are being reserved for health care workers and first responders. We rate this claim as MISSING CONTEXT, based on our research.
Our fact-check sources:
USA TODAY, Sept. 14, 2020, Wildfires burned millions of acres across the West. See what that looks like
USA TODAY, July 18, 2020, WHO agrees with more than 200 medical experts that COVID-19 may spread via the air
USA TODAY, July 5, 2020, The White House has sent conflicting messages on wearing masks and the new coronavirus cases
USA TODAY, April 3, 2020, Coronavirus live updates: Cloth masks in public now recommended; US death toll passes 7,100; nation lost 701K jobs in March
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This article originally appeared on USA TODAY: Fact check: Cloth masks ineffective in wildfires, helpful for COVID-19