Many people believe the air on a plane is stagnant and full of germs. In reality, the air in an airplane is heavily filtered and carries fewer germs than the air in most crowded spaces.
Passengers on board an aircraft breathe in a mixture of fresh air and recirculated air.
The supply of air comes from the compressor sections of the engines, it is cooled and then run through filters and then re-mixed with a fresh supply from the engine, writes pilot Patrick Smith.
Underfloor filters are used to treat the cabin air are described by Boeing as being of 'hospital quality' and capturing between 94 and 99.9 percent of airborne microbes.
Source of information: Daily Mail