Second-hand smoke exposure and coronary artery calcification among non-smoking adults

Background: Exposure to second-hand smoke (SHS) is an exposure to air pollution of fine particulate matter, carcinogens, and various toxins, affecting large parts of the population. SHS increases the risk for acute cardiovascular events and may contribute to the development of atherosclerosis. We investigate the association of SHS with coronary artery calcification (CAC). Methods: In the present cross-sectional analysis, we used baseline data (2000–2003) of 1,891 never smokers, aged 45 to 75 years, from an ongoing, prospective, population-based cohort study in Germany. Frequent SHS at home, at work and in other places was assessed by questionnaire. CAC was measured by electron-beam computed tomography. We conducted multiple linear regression analysis using exposure to SHS (any location) as the explanatory variable and ln(CAC+1) as the response variable, adjusting for gender, age, socio-economic status, and cardiovascular risk factors. Results: Frequent exposure to SHS was reported by 21.7% of respondents. After adjustment for age, gender, and socio-economic status, (CAC +1) was 25.9% (95% CI: –1.0 to 60.2%) higher in the exposed than in the unexposed. Inclusion of further cardiovascular risk factors (diabetes, cholesterol, body mass index, physical activity) reduced the estimate (19.7%; 95% CI: –5.4 to 51.5%). Highest effects were seen for exposure at home (35.8%; 95% CI –2.8 to 89.8%). The effect of SHS was comparable to up to 3 years of older vascular age, depending on age-range and sex. Conclusions: Our study provides first suggestive evidence of an association between exposure to SHS and coronary atherosclerosis. Considering the widespread exposure and the clinical relevance of coronary atherosclerosis, this result, if confirmed, is likely to be of high public health importance.