Abstract :
BACKGROUND: Few studies have examined the relationship between long-term exposure to ambient fine particulate matter ([PM.sub.2.5]) and nonaccidental mortality in rural populations. OBJECTIVE: We examined the relationship between [PM.sub.2.5] and nonaccidental and cardiovascular mortality in the U.S. Agricultural Health Study cohort. METHODS: The cohort (n = 83,378) included farmers, their spouses, and commercial pesticide applicators residing primarily in Iowa and North Carolina. Deaths occurring between enrollment (1993-1997) and 30 December 2009 were identified by record linkage. Six-year average (2001-2006) remote-sensing derived estimates of [PM.sub.2.5] were assigned to participants' residences at enrollment, and Cox proportional hazards models were used to estimate hazard ratios (HR) in relation to a 10-[micro]g/[m.sup.3] increase in [PM.sub.2.5] adjusted for individual-level covariates. RESULTS: In total, 5,931 nonaccidental and 1,967 cardiovascular deaths occurred over a median follow-up time of 13.9 years. [PM.sub.2.5] was not associated with nonaccidental mortality in the cohort as a whole (HR = 0.95; 95% CI: 0.76, 1.20), but consistent inverse relationships were observed among women. Positive associations were observed between ambient [PM.sub.2.5] and cardiovascular mortality among men, and these associations were strongest among men who did not move from their enrollment address (HR = 1.63; 95% 0.94, 2.84). In particular, cardiovascular mortality risk in men was significantly increased when analyses were limited to nonmoving participants with the most precise exposure geocoding (HR = 1.87; 95% CI: 1.04, 3.36). CONCLUSIONS: Rural [PM.sub.2.5] may be associated with cardiovascular mortality in men; however, similar associations were not observed among women. Further evaluation is required to explore these sex differences. http://dx.doi.org/10.1289/ehp.130727