Face coverings do not cause unsafe levels of oxygen or harmful carbon dioxide levels to the wearer, OSHA said in a recent list of frequently asked questions addressing the use of face masks in the workplace.

“Medical masks, including surgical masks, are routinely worn by healthcare workers throughout the day as part of their personal protective equipment ensembles and do not compromise their oxygen levels or cause carbon dioxide buildup,” OSHA in the FAQs posted on its website.

OSHA generally recommends that employers encourage workers to wear medical masks or cloth face coverings at work to help prevent spread of the coronavirus.

They are mandatory in Connecticut workplaces.

The agency said it posted the FAQs “to address inaccurate claims that these masks and face coverings cause unsafe oxygen or harmful carbon dioxide levels for the wearer.”

Design Features

Face masks are designed to be breathed through and can protect against respiratory droplets, which are typically much larger than tiny carbon dioxide particles, OSHA said.

That’s why most CO2 particles will either go through the mask or escape along its loose-fitting perimeter.

Some CO2 may collect between the mask and the wearer’s face, but not at unsafe levels.

Face coverings are especially important for someone who has COVID-19 but doesn’t know it, OSHA said.

False Claims

OSHA said that some people have mistakenly claimed that its respiratory protection standard, its permit-required confined space standard, and its air contaminants standard apply to the issue of oxygen or carbon levels resulting from the use of medical masks or cloth face coverings in work settings under normal ambient air, such as healthcare settings, offices, retail, and construction.

These standards do not apply to wearing medical masks or cloth face coverings in work settings in normal ambient air.

These standards would only apply to work settings with known or suspected sources of chemicals, like manufacturing facilities, or where workers are required to enter into a potentially dangerous location, such as a large tank or vessel.


For more information, contact CBIA’s Phillip Montgomery (860.244.1982).