Many misconceptions regarding masks and the science behind them exist that have caused many workers to be seriously concerned about their health.
According to OSHA, workers need not fear being deprived of oxygen nor being concerned about a build-up of carbon monoxide (CO).
Medical masks, including surgical masks, are routinely worn by healthcare workers throughout the day as part of their personal protective equipment (PPE) ensembles and do not compromise their oxygen levels or cause carbon dioxide buildup.
Masks are designed to be breathed through and can protect against respiratory droplets, which are typically much larger than tiny carbon dioxide particles.
Consequently, most carbon dioxide particles will either go through the mask or escape along the mask’s loose-fitting perimeter. Some carbon dioxide might collect between the mask and the wearer’s face, but not at unsafe levels.
Like medical masks, cloth face coverings are loose-fitting with no seal and are designed to be breathed through. In addition, workers may easily remove their medical masks or cloth face coverings periodically (and when not in close proximity with others) to eliminate any negligible build-up of carbon dioxide that might occur.
Cloth face coverings and medical masks can help prevent the spread of potentially infectious respiratory droplets from the wearer to their co-workers, including when the wearer has COVID-19 and does not know it.
Some people have mistakenly claimed that OSHA standards (e.g., the Respiratory Protection standard, 29 CFR 1910.134; the Permit-Required Confined Space standard 29 CFR 1910.146; and the Air Contaminants standard, 29 CFR 1910.1000) apply to the issue of oxygen or carbon dioxide levels resulting from the use of medical masks or cloth face coverings in work settings with normal ambient air (e.g. healthcare settings, offices, retail settings, construction).
These standards do not apply to the wearing of medical masks or cloth face coverings in work settings with normal ambient air).
These standards would only apply to work settings where there are known or suspected sources of chemicals (e.g., manufacturing facilities) or workers are required to enter a potentially dangerous location (e.g., a large tank or vessel).