It's pretty clear to me that the US cycling team wore masks in the Beijing airport to make a political or environmental statement of some kind. While I don't agree with the statement itself, I could at least respect their statement if they owned up to it. Instead, they refuse to admit they were making a statement of any kind - claiming they were just taking "precautionary" measures. This claim is so insane, it is almost hard to put into words. I've been to Beijing. If you are outside the air quality is pretty poor, but the airport is big, modern, and has air quality that is similar to the inside of your home.