It inspired me to do some research and I discovered some things, for example about masks and CO2. This is all in response to a comment from Yoxa:
Some days the comments are a swamp of misinformation. One simple example was a recent comment about carbon dioxide building up behind a mask. That's false. CO2 passes in and out of a mask just the same as all the other gases in the air you're breathing. If it didn't, you would die in short order.
Yoxa conveniently forgets about the dead air space behind a mask. Depending on how tightly the mask fits, only some of the CO2 exhaled from the last breath is replaced by fresh air before the next inhale begins. This dead air space comprise a significant volume of a typical inhale. And the resort to extremes ("die in short order") ignores the range of possibilities including chronic exposure to moderately elevated CO2 levels in those who wear masks daily for long periods (kids in school and unfortunately out of school even out of doors).
First, CO2 is present at a bit over 400 parts per million (ppm) in inhaled air and 3.8% or 38,000 ppm in exhaled air.
Link 1 Link 2
Second, my rough estimate for the amount of air trapped between a mask and your face: surgical mask: 10cm high x 15 cm wide x 1.67 cm deep = 250 cubic cm (cc). KN95 is deeper, so let's say 350 cc.
Third, typical
volume of a breath is 500 cc (look at tidal volume in the table).
Given that, and assuming no mixing between air trapped against the face and outside air in the 1 second or so between the end of the exhale and the beginning of the inhale, we get an upper limit of possible CO2 concentrations in inhaled air:
- cloth or surgical mask: 250 cc of trapped mask air and 250 cc of fresh air gives us 0.5 * 38000 ppm + 0.5 * 400 ppm = 19200 ppm. Of course there will be some mixing of mask air with fresh air, so the actual number will be considerably lower, depending mostly on how tight the mask fits the face.
- KN95: 350 cc of mask air, 150 cc of fresh air 350/500 * 38,000 ppm + 150/500 * 400 ppm = 26,720 ppm. If the KN95 fits well, there will be very little mixing and the actual value will not be much lower.
Now on to some studies:
The first study says this in the abstract:
In this study, the carbon dioxide concentration in the breathing zone was measured while wearing a surgical mask, a KN95 and a cloth mask. For the surgical mask, the concentration was determined under different conditions (office work, slow walking, and fast walking). Measurements were made using a modified indoor air quality meter equipped with a nondispersive infrared (NDIR) CO2 sensor. Detected carbon dioxide concentrations ranged from 2150 ± 192 to 2875 ± 323 ppm. The concentrations of carbon dioxide while not wearing a face mask varied from 500–900 ppm. Doing office work and standing still on the treadmill each resulted in carbon dioxide concentrations of around 2200 ppm. A small increase could be observed when walking at a speed of 3 km h–1 (leisurely walking pace). Walking at a speed of 5 km h–1, which corresponds to medium activity with breathing through the mouth, resulted in an average carbon dioxide concentration of 2875 ppm. No differences were observed among the three types of face masks tested. According to the literature, these concentrations have no toxicological effect. However, concentrations in the detected range can cause undesirable symptoms, such as fatigue, headache, and loss of concentration.
And the main summary figure:
Levels of CO2 were in the 2000-3000 PPM range. The bolded text, however suggests that symptoms are present for many. I argue that these point to possible long-term problems of frequent and prolonged mask wearing.
Now for the
second study:
The black line shows no-mask values. Blue is for a powered respirator. Red is for a KN95. Black is for a valved respirator (I assume a reusable rubber face mask or an N95 with an exhalation valve). These values are in percent and are much larger. The KN95 value is 2.6% or 26,000 ppm, nearly identical to my rough calculation. Note that the value exceeds the NIOSH 8 hour exposure limit by a large margin and is not far below the 15 minute exposure limit. This suggests that KN95 masks should not be worn for longer than 15 or at most 30 minutes. Of course there is the question of the difference between the two studies. But I think we've all experienced the breathlessness that comes from wearing an N95 or KN95 and even a surgical or cloth mask.
Finally, I'll link to
this study which is a review of many, many mask studies on many different aspects of mask wearing. I skimmed through it in about 10 minutes, but I think it's worth reading thoroughly. It does suggest that I overestimated dead air space significantly, but also failed to account for the dead air space in the respiratory tract. And here is
one more that is worth the read, more of an opinion piece, but with links to real studies.
So lots of downside, so those masks better work, but even the CDC's data (not from randomized controlled trials) shows only a smallish reduction. None of the RCTs done to date show any meaningful impact of mask wearing.
A few more corrections, once again, Yoxa:
If you lived in a cold climate you could see your breath and know that your little cloud is always there even when you're breathing quietly. That cloud is much smaller with a mask. Yes, I've tested that.
But that cloud is condensation that happens after air leaves your mouth and mixes with cold ambient air. The condensation occurs on condensation nuclei which include the droplets you do exhale all the time as well as dust and, of course, viral particles. When wearing a mask, the air behind the mask is warm and condensation will not occur until the air leaves the mask or encounters the colder outer layers of the mask in which case the condensation is onto the mask.
Finally, (once again Yoxa), you keep introducing the fact that the Pfizer dose for children is smaller as if that somehow suggests or proves that this makes the vaccine safe for children. Only high quality real world data of actual impacts on children can prove that.
I think others have addressed your issues about the unvaccinated protecting themselves. We on this forum obviously do that.
