Airborne

There has long been the belief that plane travel raised upper respiratory tract infection rates because of recirculation of air, with the collective illnesses of those on board, in the closed compartment of the plane cabin.This belief is commonly held in spite of all scientific evidence to the contrary.

Agustin Fuentes, in his book "Race, Monogamy and other Lies They Told You" writes:
"It is simply not true that air on planes is predominantly recirculated or germ-laden. Modern airplanes mix some compressed air with air drawn in from outside and the mix is about 50 percent at any given time. The air is refreshed throughout the flight with very effective filters and there is a total changeover in cabin air (that is total cabin air moving through the filters) every three minutes or so. So the danger from planes and disease (unless one is seated directly next to someone who is highly contagious) is pretty minimal relative to what one risks in most large office buildings."

Despite this, and the information will known by all that colds are caused by viruses and few medications are effective and none known as good prophylaxis, an over-the -counter "therapy," called "Airborne," is taken regularly by people to prevent illnesses that air travel presumably predisposes. 

In 2008 Airborne was sued by the FTC for false advertising and paid over $30 million in fines but that year was still generating over $300 million in sales.

It could be worse. Animal sacrifice, for example.