There was a huge metastudy done by the WHO in the late 90s, looking at the effect of passive smoking. In that, only one result was found that was statistically significant.
No, it wasn't that people subject to passive smoking keeled over young, whatever the "refinements" to such studies since then. It was that, entirely contrary to expectations, for children, exposure to second hand smoke was a prophylactic against lung cancer.
Jun 7, 2007
Another decree from the nanny state
Smokers deemed inelegible to adopt children under five. Much better that they remain wards of the state. Via Tim Worstall, who notes that the do-gooders' apparent goal--protecting the young from possible lung cancer years in the future--shows they don't know what they're talking about.