Press "Enter" to skip to content

A Breath of Fresh Air

Mills College Weekly

With Spring Break fast approaching, many of us are looking forward to getting away. If you’re planning on flying over the holiday, you may be wondering if your upcoming airplane ride will leave you sniffling and sneezing your way through the holiday week. Considering that more than a billion people travel in airplanes each year, a number that’s increasing by five percent annually, trying to understand what’s happening up there in the friendly skies might be a good idea (Bloomberg).

No one can deny that a few hours on an airplane leaves one feeling parched and off kilter. But, what is it about airplanes that leaves us feeling the way we do? Most people think that the air in the cabin is the culprit.

By government regulation, the cabin pressure must be at least equal to outside air pressure at 8,000 feet. The pressurized air comes from compressor stages in the jet engines. Outside air is drawn in and pressurized; this pressurization causes the air to heat up. It is cooled by heat exchangers in the engine struts and then pushed through ducts in the wing that lead to the main air conditioning units under the floor of the cabin. Here the air is cooled further and mixed with filtered air re-circulating from the cabin. This roughly equal mixture of new and recycled air is then vented into the cabin via overhead outlets (

Inside the cabin, the air moves in a circular pattern, leaving through floor grilles that lead to the lower fuselage. Here, about half of the air is released to the outside environment. The half that stays is filtered and mixed with incoming fresh air ( But still the question remains, can the air make us sick?

According to a study published in the Journal of the American Medical Association, re-circulated airplane cabin air doesn’t cause more colds. Several researchers from UCSF compared over 1,000 passengers flying between San Francisco and Denver. Some of the flights used 100 percent fresh air while others used the standard 50-50 mix. The percentages of passengers reporting colds one week after flying were approximately equal for the two groups.

So, how do we reconcile those findings with the almost universal feeling that flying increases our risk of catching a cold or some other type of infection? Perhaps the reasons behind our feeling poorly are not attributable to recycled cabin air. When we fly we are packed in with a large number of other people. Lots of people in a small space for a long time is the primary factor in transmission of colds. We are also losing sleep and crossing time zones, two factors that have been linked to increased rates of viral infection. The air in airplane cabins also has zero humidity, a condition most of us only experience while flying (JAMA). As a result, our eyes and skin dry slightly.

Additionally, when we are in flight we are exposed to a low-pressure, low-oxygen condition called hypobaric hypoxia. The condition is thought to lower the immune system, and may be the real culprit when we talk about the air being stale and feeling sick. Researchers believe that these feelings may actually be due to hypoxia rather than stale air (Bloomberg).

So, what can we do in order to stay healthy during our Spring Break travels? Drink lots of water, both before and during your flight. Stand up, stretch, and walk around; getting your circulation going will leave you feeling less drained. Washing your hands more frequently is also a good idea. Some people like to use over the counter products that boost the immune system prior to their flight. These may be a good idea, but nothing compares to keeping your immune system strong by eating well, staying hydrated, and sleeping enough. I guess that means we don’t have to worry about our return flight, just our outbound one!