Here's another thing I will tell you: I was a Travel Agent when Northwest, in all their glory, was the first airline to go smoke free and proud of it. That opened the door to the rest of the airlines being forced into going smoke free............now the AIRPORTS are smoke free.
Well, Northwest said that their FILTERS in the PLANES were FILTHY from the smoke. After a few years, one brave soul came forward and said that THEY ARE STILL FILTHY! That re-circulated air is just full of pollutants.
Why? Because when the airlines went smoke free, they thought they didn't have to change the filters as much. Heh! And people are breathing in that foul, bacteria laden air, and all the non-smokers think that the air in planes are just fine, because gee whiz................NO ONE IS SMOKING. Wake UP people! SARS ANYONE?