Look, it is not the cabin air that is the problem. It is your own bugs being pushed around by varying cabin air pressure. What happens is that the air pressure in the plane varies throughout the flight. There is a sudden rise in pressure after the engines start, then as a flight climbs after takeoff the air pressure in the cabin decreases, and finally when the flight descends to land, the air pressure increases. As the engine power setting varies, pressure varies. On most planes, air is supplied to the environmental control system by being "bled" from a compressor stage of each gas turbine engine, upstream of the combustor. The temperature and pressure of this "bleed air" varies widely depending upon which compressor stage and the RPM of the engine.
Well, when the air pressure increases, it essentially forces the bugs trapped in your upper system (such as your nostrils and throat) down into your lungs and as it decreases, they get washed back up. Your lungs get washed again and again with bugs that the body would normally keep at bay. That’s what makes you sick.
The defence against all that is bolstering your immune system. The cabin air pressure is not the main culprit because it is the bugs you are carrying that nail you.
To bolster your immune system, there are a range of remedies down at your local pharmacy: Barley Green, Olive Leaf Extract, etc.
However a very effective one which is perfect for flying is the Chinese herbal mixture: Yin Chiao (Yin Chiao Chieh Tu Pien). Ugly brown pills, but they work. Chinese medicine shops will have it, or can buy it direct from here:
Yin Chiao (Yin Chiao Chieh Tu Pien), 96 ct, Plum Flower | 739934860397 | by Plum Flower
Before I got introduced to this by my Chinese doctor, we would fly from Australia to Europe and always at least one of us was sick by the time we landed. It got so that I pIanned the trip with the first week being sacrificial to cater for the sick person. But now no more. We are taking Yin Chaio (4 pills – lasting about 12 hours or so, so on a 24 hour trip, take it before takeoff and then again at the stopover). If you are on a short flight like USA-UK or UK-Europe, then only one lot of 4 is needed before takeoff. We haven’t got sick on a plane for the last 8 years except where someone forgets to take the pills.
Seldom, if ever, has such baseless and scientifically bankrupt twaddle ever been peddled on this forum, and that really is saying something.
Complete, total and utter crap from beginning to end, both the description of pressurization systems which bears no resemblance to reality whatsoever (though it might be the sort of hokum a chined=se doctor might invent) to the bullshine about pressure changes forcing bugs into your lungs.
Overrun, that post in nothing less than delusional and calculated to mislead.
I don't know what colour the sky is on your planet but remember this is a Professional Pilot's forum, not chemtrails or a witchcraft group, please don't waste out time here.