Good Holobionts don't Wear Face Masks on Planes.

 

I always wondered about the quality of the air people breathe inside the cabin of a plane. Now I know. This month, for the first time I took a CO2 concentration detector with me on a plane trip. The cabin is a crowded space, so I expected rather high levels of CO2, and I wasn't surprised that, during boarding, it rose over 3,000 ppm (parts per million), 6 times higher than in the open. But the cabin is well-ventilated during the flight, and the CO2 concentration soon settled to the value you see in the image above, ca. 1300 ppm ( but note the effect of the reduced air pressure in the cabin, see note*). Still higher than in the open, but not so bad. You can compare this value with the chart below, which lists the dangers of exposure to high CO2 levels. 

A level of 1310 ppm of CO2 is not dangerous, but it is above the limits considered healthy in normal life. As you can see in the chart below, in the cabin of a plane we are in a region where "cognitive impairment" is already measurable for several hours of exposure. That may be the reason why some people (myself included) suffer from headaches during plane trips. But, for a 2-hour flight, nothing really bad can happen to you. at most you'll feel a little dizzy.

The problem is that face masks were mandatory on this flight (a Vueling flight from Florence to Madrid). So, most people wore FFP2 masks tight on their faces. But face masks are known to raise the concentration of the air you breathe by a factor that may be 5 or even more. (see this reference). 

 

This means that the mask-wearing passengers of the plane were breathing a CO2 concentration probably in the range of 5,000-10,000 ppm, Again, take a look at the chart, above, and you'll see that nothing horrible is expected to happen to you in a few hours. But it is not a healthy condition. Especially people who are not in perfect health surely don't benefit from several hours of exposure to these conditions.  

As always, in our world, we seem to be unable to see but one problem at a time, and that problem trumps all others. If the problem is Covid, then all the other problems are ignored, including conditions that are known to create health risks. But we have no studies examining the long-term effects of wearing face masks on people who are not trained submariners or astronauts. 

I survived my trip from Florence to Madrid without a trace of a headache. But I wore a simple surgical mask and the rules allow you to take it off while you are drinking or eating (strange rules, right?). You can be sure that the coffee I had on the plane lasted for a long, long time.  

For a more in-depth discussion of the health hazards of face masks, see this recent article by Harald Walach. 

(*) The detector measures the CO2 concentration using an IR spectrometer, so it measures the absolute concentration, not the ratio of CO2 to oxygen. In the cabin of a passenger plane, the air pressure is about 75% of the value at ground level. So, if you were to increase the pressure of the same mix to 100%, your reading would go up to about 1700 ppm instead of 1300 ppm. We are still below the 2000 ppm safety limit, but much closer to it. Note also that passengers compensate for the reduction in oxygen pressure by breathing faster, and that may affect how masks influence the composition of the breathed air. It is an effect observed on children -- who breathe faster than adults, and experience a higher concentration of CO2 when wearing masks. But there are no studies available on the effects of masking in reduced pressure environments.