WindowSeat123

Seems like people get sick not so much from cabin air itself than other variables (low pressure and cabin dryness).

Interestingly, the air might actually be cleaner than the air in your own home. If I am not mistaken, the air you get inside a plane is 50% recycled and 50% fresh from the engine compressor. Furthermore, most (but not all) commercial aircraft in the US are fitted with filters called HEPA (High Efficiency Particulate Air) with effectively removes microscopic particles, bacteria and viruses.

Of course, its not perfect. If you seat next to or within several rows of someone with an infectious disease spread by airborne transmission, then you might be at risk, as TB or SARs demonstrated. Although arguably the greater risk of infection comes from diseases that spread not by air but by physical contact. From touching another passenger with the illness or eating airline meals with contaminated eating utensils.

And of course, there is the nasty danger of getting food-borne illness from the meal you ate on the plane. Can you imagine the horror of having 200+ passengers all suffering from food poisoning and having to go to the toilet more or less at the same time? Thankfully, such incidents are relatively rare (as food safety regulations for airline meals are fairly stringent) but it has occurred in the past.

Lest I scare all of you here, the risk of catching something from your last flight is still reasonably low, and chances are getting sick soon after a flight might be from another cause.