I am with O'Leary on this one. I posted on another thread that an analysis of the risk of contagion on flights was carried out during the SARS crisis. If you search for Air China 112 on Google you will find an example, which led to the the conclusion that there was risk of infection over multiple rows (the two row rule). I think masks for everyone may be one way to go. A basic fact that a lot of people don't seem to have understood is that the mask provides the wearer with very little protection, but everyone else is considerably better protected if that person is infectious. The example I was given was that if you get on your packed train wearing a mask you are probably reducing your risk by less then 10%, but if you and everyone else is wearing masks your risk is reduced by over 90%.