The claim: Cloth masks will dangerously reduce oxygen levels, and masks don't work.
There are a lot of claims circulating on social media about the effectiveness of different kinds of face masks. A recent viral post that includes a long text allegedly written by someone "OSA 10&30 certified," sometimes along with an image with writing on a car’s rear window, takes it a step further by claiming masks can cause brain damage, headaches and high blood pressure by reducing a person’s oxygen intake to dangerous levels.
Required oxygen levels
The first claim the image made was that the Occupational Safety and Health Administration requires employers to keep oxygen levels in their work environments at a minimum of 19.5%.
The air we breathe is about 21% oxygen, 78% nitrogen and 1% other gases including carbon dioxide and neon, according to NASA.
OSHA states in its preamble to a document called the Respiratory Protection Standard that going below 19.5% can cause “increased breathing rates, accelerated heartbeat and impaired thinking” as well as “impaired attention, thinking, and coordination, even in people who are resting.”
However, the more detailed part of the claim are more false than true.
Do masks reduce oxygen intake? Are they safe for work?
The image claims wearing a mask puts a person’s oxygen intake below OSHA’s required levels and can cause brain damage, high blood pressure and headaches.
USA TODAY previously fact checked whether masks can cause these kinds of symptoms, and found that both cloth and surgical masks are unlikely to cause a dangerous drop in oxygen intake because they are not tight fitting.
Dr. Kelli Randell, an internist and medical advisor at Aeroflow Healthcare, told Health.com that any mask used for a long time has not caused carbon dioxide to build to a toxic level in otherwise healthy people.
Does OSHA say anything about the dangers of wearing a mask at work?
Yes. What OSHA states on its COVID-19 FAQ webpage is masks may not be appropriate for certain kinds of workers. “For example, cloth face coverings could become contaminated with chemicals used in the work environment, causing workers to inhale the chemicals that collect on the face covering.” according to OSHA.
The agency recommended alternative protections such as clear face shields. OSHA also states on its website that cloth masks cannot not be used as substitutes for required PPE.