>Secondhand smoke causes approximately 3,400 lung cancer deaths and 22,700-69,600 heart disease deaths in adult nonsmokers in the United States each year.

From a purely scientific perspective, how are they making the estimations on heart disease?

Additionally, whats the likelihood of getting lung cancer if you don't live with smokers, aren't a waiter/frequently exposed to second hand smoke/don't smoke yourself?

I'm just curious if there's any science behind this at all, because frankly the numbers look like bunk to me. You're telling me with the vast amount of people in this country daily exposed to second hand smoke there's a whopping 3400 lung cancer deaths? That's incredibly low...And somehow, they're attributing heart disease to second hand smoke in excess of 20,000 people? On what basis? On the basis of living with a smoker?