I hate traveling by plane for many reasons, mainly because of the cramped seats, the security theater one has to go through, and so on, though the convenience of getting to one’s destination so much more quickly usually outweighs the negative elements. I have a rule of thumb that says that if traveling by car to a destination takes six hours or less, or if there is no time constraint for even longer journeys, I prefer to drive.
Being afraid of picking up germs from other passengers has not been on the top of my list of concerns about air travel. I tend to ignore the risks of germs in normal life. But it is clear that fear of such germs has gripped many people. As a result of the recent fears about SARS and swine flu and bird flu epidemics, our university now installs anti-bacterial soap dispensers all over the place and I notice that the local supermarket provides such wipes and people use them to wipe down the handles of the shopping carts. I never use them.
To the extent that I thought about airplane germs, I thought that the greatest danger came from the air that was circulating in the confines of the cabin, due to having the vague idea that it was ‘recirculated’. But Robert T. Gonzalez explains that the air in the cabin is in fact likely to be cleaner than that in your typical office building, and that passengers have a very misguided idea of what recirculated air means.
In reality, however, the air you breath on a typical airplane flight is thoroughly clean. Fresh air from outside the plane is continuously drawn into the cabin via what are known as compressor stages in the jet’s engines. These stages compress the very cold and extremely thin air from outside the plane until its pressure matches that of the cabin. Pressurizing the air also heats it up, so it’s cooled back down before passing through High-Efficiency Particulate Air (HEPA) filters (which remove a minimum of 99.97% of any airborne particulates, bacteria and viruses) and combining with recirculated cabin air.
But there’s that word again. Recirculated.
Yes, the fresh air from outside the plane combines with some air that’s already been making the rounds in the cabin for a little while — but that circulating air started out as fresh external air itself, and it too has been cycling through HEPA filters. What’s more, recirculating cabin air is continuously released from the plane via outflow valves, so air inside the plane is constantly being replaced by the fresh air from outside. In fact, the average airplane’s cabin air is completely refreshed about 20 times per hour. By comparison, the air in your average office building (which is also typically HEPA-filtered) is refreshed just 12 times per hour. In other words, the air you breathe at cruising altitude is most likely significantly cleaner than just about any you’re liable to find on the ground.
This does not mean that air travel is more germ-free than everyday life. It is not. But the dangers come from other things like contact with surfaces that other people may have touched and Gonzalez describes the sources of the problem and what one can do about it.
I am not likely to follow his recommendations to use hand-sanitizers and the like, though. I tend to be the kind of person for whom taking a lot of steps to protect oneself from the environment is a lower priority than simply living one’s life with the minimal hassle and disruption.
Other people may arrive at a different conclusion.