It's common sense that frequent passive smoking is a risk factor for lung cancer, ischaemic heart disease, asthma and chest infections. But every one of these conditions has other causes. Conversely not all active smokers get cancer, never mind the other diseases.
The "600,000 deaths" headline is scare tactics by the WHO and those who quote them. The small print tells us that 379,000 deaths from ischaemic heart disease is an "estimate". Maybe it was 380,000 then ... They don't say how the other known risk factors were ruled out. It can be hard enough to do that with active smokers. I'm not defending passive (or active) smoking. But I'm not convinced that figures for worldwide deaths which can't be proved, or other scare tactics like pictures of lung cancer on cigarette packets, are the best way to reduce worldwide smoking.
