ETS exposure was not found to significantly increase risk among never smokers in this study, however, several potential explanations are possible. ETS exposure either as a child or an adult in the home or the workplace has been evaluated in numerous studies . The results, however, have been inconsistent as to the significance and magnitude of the effects among never smokers. When estimates were pooled in a meta-analysis of 34 case-control studies of non-smokers, a pooled relative risk of 1.2 (95% CI 1.1-1.4) was observed, although only seven out of 34 studies reporting significantly elevated risk . It was suggested that the inconsistency in the significance of findings across studies could be due to issues of sample size, measurement error, recall bias and confounding . Despite our efforts to minimize misclassification bias by collecting data on involuntary tobacco smoke exposure data for home, work and other exposure locations during both childhood and adulthood, the possibility of these issues cannot be excluded.They do find exposure to welding equipment, solvents & paints, and soot/woodsmoke are associated with increased risk of lung cancer. But not environmental tobacco smoke. There doesn't seem to be nearly as much handwringing about any of the other findings as there is about the failure to find an effect of ETS.
To the extent that we really really care about the harms to which workers expose themselves in the workplace, we should have moved to ban workplace exposure to welding equipment and paints before banning smoking in bars and restaurants. Or require that welding shops and panelbeaters have air ventilation systems more powerful than those that were required in restaurants back when they were allowed to have non-smoking sections.
Surprisingly, playing in the shop with the welder when I was a kid has increased my chances of lung cancer by more than did my parents' smoking. Not that I regret having played with the welder. Few things are more worthwhile for a boy than messing about with welders....
Update: Do read Church of Rationality on this one - very nice analysis.