Ambient PM2.5 and Risk of Hospital Admissions Do Risks Differ for Men and Women?

Background: While strong evidence exists for associations between fine particles (PM2.5) and health, less is known about whether associations differ by sex. Methods: We used Bayesian hierarchical modeling to estimate associations between PM2.5, based on ambient monitors, and risk of cause-specific cardiovascular and respiratory hospitalizations for about 12.6 million Medicare beneficiaries (>65 years) residing in 213 US counties for 1999-2010. Results: Point estimates were higher for women than men for almost all causes of hospitalization. PM2.5 risks were higher for women than men for respiratory tract infection, cardiovascular, and heart rhythm disturbance admissions. A 10 g/m(3) increase in same-day PM2.5 was associated with a 1.13% increased risk of heart rhythm disturbance admissions for women (95% posterior interval [PI]: 0.63%, 1.63%), and 0.03% for men (95% PI: -0.48%, 0.55%). Differences remained after stratification by age and season. Conclusions: Women may be more susceptible to PM2.5-related hospitalizations for some respiratory and cardiovascular causes.