Air travel imposes a pressure differential on take off and landing from altitude. As long as your tubes into your neck from behind the drums are open and working you will have equalized it in less than a hour. Its not much different than going over high mountains on the road. Go from 5000 feet to 14000 and back down your ears will pop both ways. (Which is good)
Worse case scenario gum sometimes helps. However Nature takes care of the pressure differences in a short time after the flight. Since I am already deaf, losing the remaining hearing is not a problem because it's temporary.
Airplanes treat people somewhat different when flying. If you are at about 37000 feet up your cabin will have a certain pressure that will make your body think you are somewhere near 10,000 feet up. Its not a problem usually. Do not forget to bring a mask and be on good behavior if you have to fly. Airlines will throw you off and have you arrested very easily these days if you caused problems. They don't give warnings for those who misbehave.
As far as the air and people with you in the plane generally the engines provide the cabin air and it is filtered to some degree. However you are in a tube with hundreds of people with you however many hours or a whole day for really long haul flights. Everyone has the same air and all thats in it
Personally I do not fly commercial airlines anymore its not worth the trouble.
