The Cabin Environment
In all modern pressurized aircraft, half the cabin air is fresh air drawn in via the engines with the other half recirculated from the cabin. The recirculated air is ducted through an air filter before being reintroduced into the cabin. There is a total air change (filtered recirculated plus outside air) every 2 - 3 minutes or 20 to 30 exchanges per hour. This is far more than for any home or office building and easily maintains cabin contaminants to low levels. Several studies of the past l0 - 15 years have confirmed that the levels of volatile organic compounds (solvents), airborne particulates, carbon monoxide, carbon dioxide, ozone and microbials were well within acceptable health levels of our regulatory agencies. This does not mean the air is 'allergy-safe' by any means--see below.
Aircraft cabin relative humidity is usually less than 20%, which is fairly dry. Although these low levels may be a source of mild discomfort (dry skin and eyes), there is little risk to your health. Minimize discomfort from dryness by
For those susceptible to motion sickness
Because of crowding in some aircraft, passengers are frequently uncomfortable and unable to stretch or easily leave their seats. In susceptible individuals, prolonged periods of immobility, can increase the risk for blood clots to form in the legs. This can occur in a train, car, bus, or aircraft. Consequently, it is called travelers thrombosis. There is no epidemiological evidence of a particular link with air travel itself. Travelers' thrombosis can cause pain and/or swelling of the legs during travel or even several days or weeks afterwards. Clots in the legs are not serious in themselves, but occasionally they break off and travel to the lungs causing what is called pulmonary embolism. This is not a common occurrence but when it does happen, it can be life threatening. Nevertheless, a few simple tips might decrease the risk: