| Mortality Risk Associated with Short-Term Exposure to Traffic Particles and Sulfates Dan Maynard,1 Brent A. Coull,1 Alexandros Gryparis,1 and Joel Schwartz2,3 1Department of Biostatistics, 2Department of Environmental Health, and 3Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA Abstract
Background: Many studies have shown that airborne particles are associated with increased risk of death, but attention has more recently focused on the differential toxicity of particles from different sources. Geographic information system (GIS) approaches have recently been used to improve exposure assessment, particularly for traffic particles, but only for long-term exposure. Objectives: We analyzed approximately 100,000 deaths from all, cardiovascular, and respiratory causes for the years 1995–2002 using a case–crossover analysis. Methods: Estimates of exposure to traffic particles were geocoded to the address of each decedent on the day before death and control days, with these estimates derived from a GIS-based exposure model incorporating deterministic covariates, such as traffic density and meteorologic factors, and a smooth function of latitude and longitude. Results: We estimate that an IQR increase in traffic particle exposure on the day before death is associated with a 2.3% increase [95% confidence interval (CI) , 1.2 to 3.4%] in all-cause mortality risk. Stroke deaths were particularly elevated (4.4% ; 95% CI, –0.2 to 9.3%) , as were diabetes deaths (5.7% ; 95% CI, –1.7 to 13.7%) . Sulfate particles are spatially homogeneous, and using a central monitor, we found that an IQR increase in sulfate levels on the day before death is associated with a 1.1% (95% CI, 0.1 to 2.0%) increase in all-cause mortality risk. Conclusions: Both traffic and powerplant particles are associated with increased deaths in Boston, with larger effects for traffic particles. Key words: air pollution, black carbon particles, fine particles, GIS-based exposure, land use regression, mortality, particulate matter, traffic. Environ Health Perspect 115:751–755 (2007) . doi:10.1289/ehp.9537 available via http://dx.doi.org/ [Online 29 January 2007]
Address correspondence to J. Schwartz, Department of Environmental Health, Exposure Epidemiology and Risk Program, Harvard School of Public Health, 401 Park Dr., Landmark Center, Suite 415, PO Box 15698, Boston, MA 02215 USA. Telephone: (617) 384-8752. Fax: (617) 384-8745. E-mail: joel@hsph.harvard.edu We are thankful for the input of S. Melly and H. Suh. This work was funded by the National Institute of Environmental Health Sciences (ES09825/ES012004/ES00002) , and the U.S. Environmental Protection Agency (R827353) . The authors declare they have no competing financial interests. Received 20 July 2006 ; accepted 29 January 2007.
The full version of this article is available for free in HTML or PDF formats. |
