Association between long-term exposure to Sulfur dioxide pollution and hypertension incidence in northern China: a 12-year cohort study.

Several studies have researched the short-term effect of sulfur dioxide (SO2) exposure on hypertension. However, no evidence has provided the relationship between long-term high pollution exposure of SO2 and morbidity of hypertension in cohort studies in China. This retrospective cohort study aimed to evaluate this association. We used Cox proportional hazards regression models to examine the hazard ratios (HR) for hypertension risks from 1998 to 2009 associated with accumulative exposure of air SO2 among adults in northern China. Annual average concentrations of sulfur dioxide (SO2) were obtained from 15 local environmental monitoring centers. Hypertension was identified according to self-reported diagnostic time and treatment for hypertension with anti-hypertensive medication. Among 37,386 participants, 2619 new cases of hypertension were identified during 426,334 person-years. In the fully adjusted model, HR and 95% confidence interval (CI) of hypertension incidence for each 10 μg/m3 increase in SO2 were 1.176 (1.163 and 1.189). Results from stratified analyses suggested that effects of SO2 on hypertension morbidity were more pronounced in participants < 60 years old, tea drinkers, and those with high education, high poultry consumption, and active (occasional and frequent) exercise. We found that long-term exposure to high levels of SO2 increased the risk of incidence of hypertension in China.