Mortality in the Medicare population and chronic exposure to fine particulate air pollution in urban centers (2000-2005).
BACKGROUND
Prospective cohort studies constitute the major source of evidence about the mortality effects of chronic exposure to particulate air pollution. Additional studies are needed to provide evidence on the health effects of chronic exposure to particulate matter < or = 2.5 microm in aerodynamic diameter (PM(2.5)) because few studies have been carried out and the cohorts have not been representative.


OBJECTIVE
This study was designed to estimate the relative risk of death associated with long-term exposure to PM(2.5) by region and age groups in a U.S. population of elderly, for the period 2000-2005.


METHODS
By linking PM(2.5) monitoring data to the Medicare billing claims by ZIP code of residence of the enrollees, we have developed a new retrospective cohort study, the Medicare Cohort Air Pollution Study. The study population comprises 13.2 million participants living in 4,568 ZIP codes having centroids within 6 miles of a PM(2.5) monitor. We estimated relative risks adjusted by socioeconomic status and smoking by fitting log-linear regression models.


RESULTS
In the eastern and central regions, a 10-microg/m(3) increase in 6-year average of PM(2.5) is associated with 6.8% [95% confidence interval (CI), 4.9-8.7%] and 13.2% (95% CI, 9.5-16.9) increases in mortality, respectively. We found no evidence of an association in the western region or for persons > or = 85 years of age.


CONCLUSIONS
We established a cohort of Medicare participants for investigating air pollution and mortality on longer-term time frames. Chronic exposure to PM(2.5) was associated with mortality in the eastern and central regions, but not in the western United States.
Zeger
Scott L
SL
Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
Dominici
Francesca
F
McDermott
Aidan
A
Samet
Jonathan M
JM
D000368:Aged; D000369:Aged, 80 and over; D000397:Air Pollution; D015331:Cohort Studies; D004781:Environmental Exposure; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D006801:Humans; D006278:Medicare; D009026:Mortality; D010316:Particle Size; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology; D014504:Urban Health