Have you heard the myth that you may inhale more CO2 than oxygen when you wear an anti-pollution mask – by re-breathing your exhaled air?
For this myth, some people are avoiding a mask. Is this Right or wrong?
Do Anti-pollution masks cause you to inhale more CO2?
Absolutely wrong!!
On this page we answer:
- Does wearing a mask make you inhale more carbon dioxide?
- Why do some Doctors actually recommend masks that RE-circulate CO2 to high performing athletes for improved lung function?
Does wearing a mask make you inhale more carbon dioxide?
“Only if the mask actually holds gas without leaking. Particle Filtration masks are so porous they don’t hold CO2 or other gases inside mask from mixing with the air outside the mask. Last of any breath you exhale from lower lung called end-tidal breath has approx 100x more CO2 than inhaled in fresh air (40000ppm vs 400).
If exhaled into a tight-fitting partial rebreather mask designed to capture the last 100–300ml without leaking (think snorkel; since CO2 is heavier than air it will stay in the bottom of the snorkel for rebreathing even if the top end is left open to air)
The effect on those who wear masks is to automatically, reflexively increase the volume of breathing per minute, known as minute ventilation, approximately 40% within a few minutes. This happens as a high level of CO2 rebreathed from mask headspace at the start of each inhalation triggers carotid reflex .to breathe more deeply. No conscious effort is required. Among indications are collapsed people at risk of dying from respiratory failure from overdoses of opiates, alcohol or carbon monoxide. If their heart is still beating they don’t need CPR but do need some respiratory stimulant. CO2 from rebreathing can be that stimulant.”
Albert Donnay, Toxicologist & Env.Health Engineer
Does wearing a mask make you inhale more carbon dioxide?
If you wear a snorkel,
This does slightly increase dead space and hence hampers breathing a bit by making the air reaching the lungs have slightly more CO2. But since humans can tolerate a much higher level of CO2 than found in the atmosphere, it would take a very long snorkel to make the CO2 levels in inspired air significantly higher. And a swimmer using a snorkel that long would run into problems with water pressure long before problems with dead space.
A mask is similar. It slightly increases dead space too but since its porous, the volume of dead space is slightly less than the volume of space in between the mask and your face.
250-350ppm is the normal background concentration of CO2 in outdoor ambient air. 5,000 ppm is the workplace exposure limit (as 8-hour TWA) in most jurisdictions. That’s over 14 times the normal CO2 levels. So it would take a dead space increase of a very large volume to cause serious problems.
What is Dead Space?
There is something called “dead space” in respiration.
Dead space (physiology) – Wikipedia
This is an analogy using a syringe
The volume shaded in red is the dead space. Assuming both syringes are the same volume (say 5 ml) let us imagine that they are the lungs. First we “exhale” or press the plunger on the syringe fully. The dead space contains “expired air” or air that is slightly richer in CO2. Now we “inhale”. The syringe on the left contains 5ml of air composed of 4.998 ml of room air mixed with 0.002ml of expired air. The one on the right also contains 5ml but it is made up of 4.916 ml of room air + 0.084 ml of expired air. The syringe on the right contains air that has slightly more CO2 than the left. If we added more dead space like say attaching a small hose to the end of the syringe then the contents of the syringe get higher and higher concentrations of CO2. If the hose you attach is > 5ml then pretty much zero outside air will enter the syringe, it will just be “rebreathing” its own expired air.
From: Vincent Maldia
Why do some Doctors actually recommend masks that RE-circulate CO2 to high performing athletes for improved lung function?
Using the mask when training forces your heart and lungs to work harder. When you remove the mask for a race or game, your body uses oxygen more efficiently. Fans of altitude masks claim that using them can improve speed, endurance, and strength.
Doctors actually recommend masks that RE–circulate CO2 for athletes to improve their lung function and performance capability.
Elevation masks don’t change the partial pressure of incoming air; all they do is simply reduce the total amount of airflow to the lungs. … By training in a hypoxic environment, and not changing partial pressure as altitude would, all you’re doing is improving the strength and endurance of your respiratory system
How can lung capacity be increased? Slowly breathe in, and expand your lungs to the maximum capacity. Hold the air for about 20 seconds or what is comfortable for you. While counting, place both hands on your hips with your thumbs facing front with pinkies touching the small of your back. Exhale the air slowly, relax and repeat three more times.
