Bigstan said:Neither of the above links provides evidence, the closest the BBC article gets is:
Pleas note the word could.
As for the ASH link - if someone from those tobacco fascists told me it was raining I'd look out of the window to check.
Stan
You’re going to be hard pressed to find "proof" as you put it. But it doesn't take a genius to work out that if tobacco kills 50,000 people a year, the second hand smoke isn't going to be harmless is it?
I think the fact that there are much worse pollutants out there that are carcinogenic is a better argument than trying to say that second hand smoke is harmless.