P1-355 Long-term PM2.5 air pollution exposure and mortality among California residents in the NIH-AARP cohort

Introduction Epidemiological studies indicate that exposure to fine particulate matter air pollution mass (PM 2.5 ) is associated with an increased risk of premature mortality. Pope et al (2002, 2004) reported elevated mortality risks of long-term PM 2.5 exposure in the USA nationwide American Cancer Society (ACS) CP-II cohort, finding a total mortality risk of RR=1.04 per 10 ug/m 3 (95% CI 1.01 to 1.08), and a cardiovascular mortality RR=1.12 per 10 ug/m 3 (95% CI 1.08 to 1.15). We seek to evaluate the PM 2.5 association with these outcomes in another large US cohort. Methods The NIH-AARP cohort is an ongoing prospective mortality study of more than a half million people from locations throughout the USA (Adams et al , 2006). Using available EPA data to interpolate exposures on a census tract level, we evaluated associations between PM 2.5 in California, the state with the largest number of cohort participants. The statistical approaches applied were similar to those used in the previously published ACS cohort research: standard Cox Proportional Hazards (CPH) modelling, including individual level covariates. Results The CPH estimated long-term PM 2.5 risk in this NIH-AARP cohort in California was RR=1.09 per 10 ug/m 3 (95% CI 1.05 to 1.12) for total mortality. The risk found for cardiovascular mortality was RR=1.18 per 10 ug/m 3 (95% CI 1.11 to 1.24). These confirm excesses at least as great as observed in the ACS cohort. Conclusion Analysis of mortality among California residents of the NIH-AARP cohort confirms excess total and cardiovascular risks from long-term exposure to PM 2.5 .