The Science Behind Second Hand Smoke

I would like to start out by saying that I am a non smoker and I do not like being in situations where the tobacco smoke hangs heavy in the air. I will also tell you that my mother and most of my brothers smoke, as does my son. I therefore am exposed to second hand smoke on occasion. I do not worry about it the way that the Surgeon General does. I suspect that if you know a little bit about statistics, you do not worry either.

The correlations between secondhand smoke and lung cancer are weak at best. The weaker the correlation, the more it is likely that a confounding variable is present. For example, smoking correlates strongly with income level. The richer you are, less you are likely to smoke. The poorer you are, however; the more likely you are to live near an industrial area near power plants, and other sources of pollution. A good statistician should be able to control for that, but it is impossible to control for variables that you don't know about.

Finally, the way the numbers are reported leaves me a little put off. Experts off say that breathing second hand smoke raises your chances of lung cancer by 30%. If we assume that they are correct, it sounds like there is a huge difference. It's only when you look at the incidence rate that you can tell. If my chances are one in ten million of getting lung cancer without ever breathing second hand smoke, then my chances are one in 7 million of getting lung cancer if I do breathe it. Both numbers are very small, and not that different.

So if you want to ban smoking because it is a nuisance, I say fine. If you want to ban it on the basis of its health risk, I have to ask why you aren't banning fine particulate carbon from diesel exhaust. It represents a far higher risk to the public health.