It is intuitive. When someone is breathing and a cloth is put in front of their mouth, of course they will experience breathing resistance. The air is slowed. Certainly, not as much oxygen is entering the lungs as before. Right? Certainly, more carbon dioxide is entering the lungs, right? Carbon dioxide poisoning is a legitimate concern for mask users.
This issue came to the forefront with a number of posts circulating social media, which detail the dangers of how face masks can cause carbon dioxide poisoning (hypercapnia) and a lack of oxygen (hypoxia). Many people believed the posts because of their legitimate concerns. We are after all putting cloth in front of our mouths.
The response from news agencies calling these sites’ conspiracy theories was swift. Experts were quickly called in to debunk the posts. However, perhaps they were too swift. Scientific support does exist that says masks increase the amount of carbon dioxide inhaled. A caveat to these studies will be explained.
One study reported in Nature.com assessed 106 children between 7 and 14 years of age on their FICO2 (fractional inhalation of carbon dioxide) while wearing N95 masks compared to not wearing those masks. A 20% increase in fractional carbon dioxide inhalation for low to moderate activity levels was found. Other studies on N95 masks also provide evidence that masks do cause an increase in carbon dioxide inhalation. Carbon dioxide levels do increase.
To be fair, though, a twenty percent increase is not necessarily dangerous and not necessarily carbon dioxide poisoning, and to fully understand the impact, we should understand more about the level of carbon dioxide in our environment. There are going to be a lot of numbers. They are important so bear with me.
According to the Mauna Loa Observatory in Hawaii, the average outdoor ambient carbon dioxide level in the atmosphere at present is 416 ppm, which means that for every million parts of gas in the atmosphere, 416 parts are carbon dioxide. Assuming that the inhaled breath would result in a 20% increase, the inhaled breath in an N95 mask would have approximately 520 ppm.
Numbers are just numbers. They need context. What is dangerous for humans? An article from the journal Environment International showed that physiological effects from carbon dioxide were increasingly seen from 500 ppm and upwards to 5000 ppm. Using an N95 mask would cause carbon dioxide inhalation levels at the lower end. It is important to add that indoor carbon dioxide levels are often higher. According to OSHA, levels above 600 ppm may cause complaints, and a level of 1000 ppm of carbon dioxide should be used for the upper limit of indoor activities.
It would seem reasonable to conclude that wearing an N95 mask indoors could increase the carbon dioxide levels in the mask high enough to reach a level that causes physiological effects. For healthy individuals, though, N95 masks do not seem to have effects. A study in NCBI on pregnant health care workers, who were working indoors, showed a 9% increase in the expired carbon dioxide of the workers, but the study found no measurable physiological effects on fetuses, which are particularly susceptible to environmental stress.
A study in the National Library of Medicine also supported the conclusion that although N95 masks did show reduced oxygen intake and increased levels of carbon dioxide intakes, the masks did not impose a physiological burden on healthy health care workers for one hour of use. Thus, there seems to be little support for the idea that N95 masks will cause carbon dioxide poisoning in healthy individuals. Those with respiratory problems may have effects, though, and scientific literature does not advise that they be used with activities of high exertion because they will prevent the face from cooling.
N95 masks are not normal masks, though. N95 masks are the tight fitting masks that health care providers use when working directly with Covid patients. Their name refers to their ability to filter 95% of 0.3 micron particles, which is why they are often used by people in countries of high air pollution. They are air sealed, meaning that all air exhaled and inhaled will go through the mask. Consequently, they are not advised for people with breathing problems. A review of scientific literature also suggests that when used with activities of high exertion they will prevent the face from cooling. Thus, exercising with N95 masks is not advised.
At present, although the vast majority of the states require or recommend wearing face masks, no state is recommending N95 masks. Surgical masks and cloth masks do not form that tight seal around the mouth. They also have pores, each of which is much larger than those of the N95 masks. As long as the masks aren’t wet, breathing resistance will be much less than that experienced with N95 masks.
Seeing that N95 masks have been shown to impose no dangerous physiological burdens on healthy people during low to medium activity levels, there is little rationale for believing that face masks or surgical masks will be dangerous to healthy individuals. The risk of incurring carbon dioxide poisoning due to increases of the inhalation of carbon dioxide due to a face mask would seem to be as high as breathing through a scarf in the winter.
It is interesting to note that even in pre-Covid times, the wearing of face masks has been part of many East Asian cultures. During the influenza season, crowds of Koreans and Japanese don their face masks to prevent infection. In Vietnam, China, and Thailand, N95 masks are widely used to protect the lungs against the high levels of particulate matter in the air (i.e. air pollution). Some Asian countries even consider face masks to be fashion accessories.
If face masks were dangerous, cultures of people wearing face masks should have a lower life expectancy as a whole. Yet, according to the World Bank, Japanese have a life expectancy of 84 years from birth. For Koreans, it is 82. Americans have a life expectancy of 79 years. East Asians wear masks and live longer.
Rest assured. There is no reason to believe that face masks will cause carbon dioxide poisoning. Those social media posts do appear to be exaggerated.
Now that a general understanding of carbon dioxide levels has been discussed, let’s move on to the elephant in the room, a serious threat to all humanity’s health, much greater than Covid-19. At levels of 500 ppm, carbon dioxide may show physiological effects. At levels of 600 ppm, the carbon dioxide is perceptible and some people may experience the first signs of poisoning. At present, the carbon dioxide level is 416 ppm and rising at a rate 2 to 3 ppm per year, which means it is possible that within 40 years, the Earth’s atmosphere will pass into what scientists consider to be toxic levels. An article in Current Science discusses the effects in much more depth. Those with respiratory ailments will be the first to feel the effects followed by everyone else, eventually.
Indoor carbon dioxide levels are usually higher than outdoor levels, due to less than ideal ventilation. Forty years from now, when the outdoor carbon dioxide levels are at 500 ppm, people indoors may be experiencing 600 ppm. The air will seem stale. Add an N95 mask on top of that, which can increase the carbon dioxide inhalation by 20%, and our health care providers may be experiencing more than 600 ppm regularly. Carbon dioxide poisoning will no longer be a conspiracy theory.
We are living in dire times. The level of carbon dioxide increase must be addressed not only for its effects on the climate but also for its effects on the health of people and many other animals. Even right now, carbon dioxide is causing the acidification of the oceans, which is causing shellfish to die off. According to the National Oceanic and Atmospheric Administration, the oceans are presently thirty percent more acidic than they were during pre-industrial times.
It is all about carbon dioxide. The pre-industrial era had levels of around 250 ppm, and the Earth now has 60% higher carbon dioxide levels than it did 250 years ago. Back in 1750, someone inhaling air in an N95 mask would be inhaling much less carbon dioxide than we are now without masks.
Carbon dioxide poisoning is real. People have a legitimate reason to care. Let us shift away from the discussion on face masks, which are safe, to where the real debate lies — how to reduce our country’s dependence on fossil fuels. Burning coal, natural gas, and petroleum products make carbon dioxide, and that’s basic chemistry. We have to keep the carbon in the ground and not put it in the atmosphere. We have to keep the carbon dioxide levels at safe levels, for us now and for our grandchildren.
When the nation’s talk about health care is resolved, the national topic of conversation will move onto infrastructure. Much of our infrastructure will have to be restructured to dramatically reduce its carbon intensity. Let’s get talking about carbon dioxide poisoning before it is too late.