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Mercedes Medina-Ramón,¹ Robert Goldberg,^2,3 Steven Melly,¹ Murray A. Mittleman,^4,5 and Joel Schwartz^1,4

¹Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA; ²Department of Community Health, Brown University, Providence, Rhode Island, USA; ³Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA; ⁴Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA; ⁵Cardiovascular Epidemiology Research Unit, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA

Abstract
Background: Although patients with heart failure (HF) have been identified as particularly susceptible to the acute effects of air pollution, the effects of long-term exposure to air pollution on patients with this increasingly prevalent disease are largely unknown.

Objective: This study was designed to examine the mortality risk associated with residential exposure to traffic-related air pollution among HF patients.

Methods: A total of 1,389 patients hospitalized with acute HF in greater Worcester, Massachusetts, during 2000 were followed for survival through December 2005. We used daily traffic within 100 and 300 m of residence as well as the distance from residence to major roadways and to bus routes as proxies for residential exposure to traffic-related air pollution. We assessed mortality risks for each exposure variable using Cox proportional hazards models adjusted for prognostic factors.

Results: After the 5-year follow-up, only 334 (24%) subjects were still alive. An interquartile range increase in daily traffic within 100 m of home was associated with a mortality hazard ratio (HR) of 1.15 [95% confidence interval (CI) , 1.05–1.25], whereas for traffic within 300 m this association was 1.09 (95% CI, 1.01–1.19) . The mortality risk decreased with increasing distance to bus routes (HR = 0.88 ; 95% CI, 0.81–0.96) and was larger for those living within 100 m of a major roadway or 50 m of a bus route (HR = 1.30 ; 95% CI, 1.13–1.49) . Adjustment for area-based income and educational level slightly attenuated these associations.

Conclusions: Residential exposure to traffic-related air pollution increases the mortality risk after hospitalization with acute HF. Reducing exposure to traffic-related emissions may improve the long-term prognosis of HF patients.

Key words: air pollution, epidemiology, follow-up studies, heart failure, survival. Environ Health Perspect 116:481–485 (2008) . doi:10.1289/ehp.10918 available via http://dx.doi.org/ [Online 10 January 2008]

Address correspondence to M. Medina-Ramón, Centre for Research in Environmental Epidemiology Barcelona Biomedical Research Park C/ Doctor Aiguader, 8808003 Barcelona, Spain. Telephone: 34 93 316 0400. Fax: 34 93 316 0575. E-mail: mmedina@imim.es

This research was made possible by the cooperation of the medical records, administration, and cardiology departments of participating hospitals in the Worcester metropolitan area, and was supported by National Institute of Environmental Health Sciences–National Institutes of Health (NIH) grants ES011636 and ES000002, U.S. Environmental Protection Agency grant R832416, and NIH grant R37 HL69874.

The authors declare they have no competing financial interests.

Received 25 September 2007 ; accepted 10 January 2008.