Short-term Air Pollution Levels and Blood Pressure in Older Women

Evidence of associations between daily variation in air pollution and blood pressure (BP) is varied and few prior longitudinal studies adjusted for calendar time. METHODS: We studied 143,658 postmenopausal women 50 to 79 years of age from the Women’s Health Initiative (1993–2005). We estimated daily atmospheric particulate matter (PM) (in three size fractions: PM(2.5), PM(2.5-10), and PM(10)) and nitrogen dioxide (NO(2)) concentrations at participants’ residential addresses using validated lognormal kriging models. We used linear mixed-effects models to estimate the association between air pollution concentrations and repeated measures of systolic and diastolic BP (SBP, DBP) adjusting for confounders and calendar time. RESULTS: Short-term PM(2.5) and NO(2) were each positively associated with DBP {0.10 mmHg [95% confidence interval (CI): 0.04, 0.15]; 0.13 mmHg (95% CI: 0.09, 0.18), respectively} for interquartile range changes in lag 3-5 day PM(2.5) and NO(2). Short-term NO(2) was negatively associated with SBP [−0.21 mmHg (95%CI: −0.30, −0.13)]. In two-pollutant models, the NO(2)–DBP association was slightly stronger, but for PM(2.5) was attenuated to null, compared with single-pollutant models. Associations between short-term NO(2) and DBP were more pronounced among those with higher body mass index, lower neighborhood socioeconomic position, and diabetes. When long-term (annual) and lag 3-5 day PM(2.5) were in the same model, associations with long-term PM(2.5) were stronger than for lag 3-5 day. CONCLUSIONS: We observed that short-term PM(2.5) and NO(2) levels were associated with increased DBP, although two-pollutant model results suggest NO(2) was more likely responsible for observed associations. Long-term PM(2.5) effects were larger than short-term.