I’ve heard a lot of anti-maskers use the argument that since we breathe out CO2, it will become trapped in the mask and is dangerous to breathe back in.
Obviously, this isn’t the case, because doctors wear their masks for hours and hours on end while doing surgeries. However, I am wondering, how does it work?
In: Biology
C02 is much, *much* smaller than the virus cells. C02 molecules can easily leave through the mask’s material. Like, “sausage in a hallway” easy.
Co2 is a very small molecule, just like other gases it has little difficulty traveling though a cloth barrier. If the mask was completely airtight, it would be very difficult to breathe at all.
For one, CO2 isn’t dangerous, it’s not toxic. You could suffocate if you walked into a room full of it, but that’s not the case here. You only exhale less than 5% CO2
And the volume of of air trapped in the mask is maybe 100ml.
The average residual volume of air in your lungs after exhaling is around 1200ml. That volume in the mask would simply be added to this. If around an 8% increase in this volume is going to hurt you…Well…Uhhh…Have you died recently because you breathed shallowly a few times?
The danger is when there is enough CO2 to displace the oxygen you need. All air we normally breathe has some amount of CO2 anyway, and as pointed out by others the mask doesn’t prevent CO2 or oxygen from passing through. There may be a very slight increase of inhaled CO2, but not enough to measurably reduce the amount of oxygen you inhale (which is the important part).
>I’ve heard a lot of anti-maskers use the argument that since we breathe out CO2, it will become trapped in the mask and is dangerous to breathe back in.
>Obviously, this isn’t the case, because doctors wear their masks for hours and hours on end while doing surgeries. However, I am wondering, how does it work?
1. You’re wearing a mask, not exhaling into a balloon. There is no space for anything to accumulate. Perhaps a couple of milliliters of space where the mask isn’t pressed too tightly against your skin? A typical breath will contain upwards of [500ml of air](http://www.e-breathing.com/normal-respiratory-rate-volume-chart/).
2. You don’t exhale CO2. You exhale regular air with [a concentration of oxygen that’s a bit lower and a concentration of CO2 that’s a bit higher](https://byjus.com/biology/composition-gases-breathe/).
Your mask is not hermetically sealed, it still gets out. Thats why the number 1 preventative measure is physical distancing and you wear mask as a second but less effective preventative measure if you must be around people.
You might have a slightly higher CO2 level in that air you breathe in from your mask, but it barely makes a difference. CO2 is diffused out of the blood in the lungs. Normally, you exhale air with about 4% CO2, and inhale air with about 0.04% CO2. Most masks allow CO2 to diffuse out easily, but there’ll still be some of your breath stuck between the mask and your lungs.
Your body will barely notice the difference. Remember, you already have a fair chunk of “stale” air that doesn’t get cycled with each breath. The lungs do not fully deflate, some air remains behind. And your windpipe also keeps some air in there. The added bit of air the mask traps isn’t an issue, there is still plenty of ventilation.
The only time it might become an issue is if you are breathing rapidly after exercising, or if you hyperventilate for some reason. In those cases, take off the mask and just keep your distance from people.
Think about the fact that when we perform CPR we are literally exhaling directly into their lungs. If there was enough CO2 in a human exhale to harm someone why would we perform life saving CPR with that exhale? Our exhale does have some CO2 in it but our exhale is also still full of O2, we don’t use all of the O2 we inhale and whatever isn’t used comes back out in our exhale. The average human exhale is entirely safe to breathe in, it just is, which is why we’re able to use it to save people’s lives with CPR.
The misconception exists because you exhale about 5% CO2, and that also happens to be the concentration at which CO2 starts showing toxic effects (around 5% and higher).
And this would indeed be very deadly, if you were to breathe into a plastic bag that is tied around your head.
However, that is not what you are doing. You are breathing out into a mask, which is not airtight. Even medical masks, which are layers of melted polymers and fabric, are not air tight. If they were, yes, you would die. But they aren’t. So you never breathe in that 5% CO2 concentration you breathe out.
Make no mistake – breathing with a mask could become strenuous and eventually dangerous if you require a higher air circulation, such as when performing exerting physical activity like exercising, either for a prolonged duration of time or to a high degree of exertion, as they do restrict your air circulation to a degree (at least if the mask is any good. A simpler mask like a basic dust mask will not have as strong an effect as a medical mask, and will not be as helpful against viruses either).
But when not under physical strain or any other reason that would require a higher air circulation than usual, there’s essentially no risk.
Fun fact – in small concentrations, CO2 actually serves an important role in blood vessel constriction regulation.
CO2 does not cause damage to any tissues, the only danger is it getting in the way of the O2 you need in your lungs and ultimately your brain. If you legitimately start passing out, go ahead and pull your mask down for a minute, but like everyone else is saying, those molecules won’t get stuck in any sensible mask.
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