The disease burden of secondhand tobacco smoke exposure in China and the impact of smoke-free policies at work

This dissertation consists of three major parts: the meta-analysis of lung cancer and passive smoking in China; the estimation of disease burden from tobacco smoking (including both active smoking and passive smoking) in China; and the evaluation of the effectiveness of smoke-free policy at work in China. The meta-analysis of the nineteen epidemiological studies in China on passive smoking and lung cancer found that passive smoking significantly elevated the risk of lung cancer among non-smokers. Specifically, lifetime exposure to SHS is associated with an OR of 1.63 of lung cancer and the OR of husband smoking is 1.28; both are significant at 95% confidence level. The findings from the meta-analysis were used to estimate the disease burden caused by passive smoking in China from two major diseases---lung cancer and ischemic heart disease (IHD). In 2002 passive smoking was responsible for 21,700 deaths from lung cancer and 210,000 years of life lost due to lung cancer along with 34,000 IHD deaths and more than a quarter of a million years of life lost from IHD. Passive smoking is a significant cause of mortality in China, even compared to active smoking---for lung cancer and IHD combined, the mortality caused by passive smoking is 20% of that caused by active smoking. Together active smoking and passive smoking are responsible for 1 million deaths and the loss of nearly 10 million years of life in adults each year in China, 12% and 5% of national death totals, respectively. In the last section of this dissertation, the effects of smoke-free policy on the exposure of secondhand smoke (SHS) in workplaces in China were examined. Non-smokers sharing offices with smokers in buildings with no smoking policy were exposed to a significant level of SHS (median concentration of 6.7 ug/m3). Both smoke-free policy and restrictive smoking policy were associated with reduced SHS level in the offices as well as in the entire building. Compared to buildings with no smoking policy, buildings with a smoke-free policy or a restrictive policy have much lower concentrations of SHS: offices with at least one smoker averaged 67% lower SHS concentration and offices with no smoke was detected averaged 30% lower SHS concentration in. In the building where a smoke-free policy became effective recently, the SHS level decreased significantly as a result of the policy, especially in offices (>80%) and hallways (nearly 90%). In conclusion, tobacco smoking poses serious threats to the health of both smokers and non-smokers in China. Non-smoking workers are facing significant health risks from being exposed to SHS at work. The central and local governments should pass legislation requiring smoke-free environment in all workplaces; such policies have been shown to effectively protect the health of non-smoking workers.