Do Masks Make You Breathe Too Much Carbon Dioxide?

An image being shared on social media states that hypercapnia, or breathing too much carbon dioxide, can cause symptoms like drowsiness and dizziness. That much is true, and the image comes from Wikipedia here. What’s not true is the implied relationship between hypercapnia and wearing a mask.

As a refresher, if you’re wearing a mask while out and about, it should be a cloth mask. Medical-grade N95 respirators should be reserved for health professionals, and N95s from hardware stores are not appropriate because their valves can let the virus through.

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Can a mask, cloth or otherwise, trap enough carbon dioxide to cause drowsiness or other symptoms? Fortunately, the answer is no.

Carbon dioxide is a tiny molecule, far smaller than the holes in any of these types of masks. Remember, masks stop droplets of saliva and mucus, but they still allow air to flow.

If you were wearing a plastic bag, that would be a problem, but that’s why masks are made of porous materials. The carbon dioxide can flow through them just fine. Masks can feel stuffy because your own respiratory droplets make the air around your face feel moist, but you’re not slowly poisoning yourself.

As doctor and professor Michelle Cohen points out on Twitter, the study that’s sometimes cited isn’t really relevant. It tested a very different type of mask than what we’re all wearing, and while it found that carbon dioxide levels increased somewhat, it also found that the subjects did not have any symptoms of hypercapnia.

The researchers found a small increase in exhaled CO2 after 20 min of respirator use, but none of the subjects reported feeling hypercapnic.

This was a tiny study with only 4 subjects that DIDN’T ACTUALLY STUDY the type of mask most people use.

????This is what they studied. 9/ pic.twitter.com/yM8UFwqTkx

— Michelle Cohen, MD (@DocMCohen) May 11, 2020

Again, this is a theory that doesn’t pass a sniff test. If masks really did make people feel drowsy and confused, medical professionals would walk into work, strap on their masks, and quickly become unable to do their jobs. Masks never would have become standard equipment if this were true. How could a surgeon operate for hours if they were suffering from carbon dioxide toxicity the whole time?

Meanwhile, the people who are sharing memes about hypercapnia and masks are often the same people who were arguing against masks for some different reason a few weeks ago. It’s important to ask yourself whether somebody is sharing information because it’s something that they want to believe.

That said, there are some cases where people may be unable to safely wear masks. According to the CDC, these include people who already have breathing problems, and children under two years old. If you have anxiety, the feeling of wearing a mask may feel uncomfortably similar to feelings you have during a panic attack. But if none of these apply, there’s no reason to believe wearing a mask could be harmful to your health or cognition. It might be annoying, but it’s not poisoning you.