Q. Every time I fly from Los Angeles to Australia, I get very sick. Last time, I was sick for over six weeks when I got back home. I was told that I shouldn't fly longer then a five hour flight. Something to do with the air on the planes. Is this common?

A. Actually, it’s not uncommon, especially if one is older. Studies have shown that long flights create health problems of varying degrees, usually minor. One solution is to fly in a Boeing Dreamliner 787, which has an advanced air filtration system and also flies at a low “cabin altitude” which helps passengers breathe with less effort. These cabins are also kept at a higher humidity level, which keeps eyes, mouths, and nasal passengers hydrated.  Keeping mucous membranes moist supposedly helps prevent germs and bacteria from becoming a problem. As the Australian Business Traveller states, "If your nasal passage mucous membrane cracks in-flight — common on long-haul flights — you also open the body up to a much easier pathway for germs to get in."