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Long-Term Exposure to Ambient Air Pollution and Risk of Hospitalization with Community-acquired Pneumonia in Older Adults

¹ Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada; ² Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, California; ³ Environmental Health Directorate, Health Canada, Ottawa, Ontario; ⁴ Department of Medicine, University of Alberta, Edmonton, Alberta; ⁵ School of Geography and Earth Sciences, McMaster University, Hamilton, Ontario; and ⁶ Departments of Pathology and Molecular Medicine, Michael DeGroote Institute for Infectious Diseases, McMaster University, Hamilton, Ontario, Canada

Correspondence and requests for reprints should be addressed to Mark Loeb, M.D., McMaster University, MDCL 3200, 1200 Main St. W., Hamilton, ON, L8N 3Z5 Canada. E-mail: loebm{at}mcmaster.ca

Rationale: Little is known about the long-term effects of air pollution on pneumonia hospitalization in the elderly.

Objectives: To assess the effect of long-term exposure to ambient nitrogen dioxide, sulfur dioxide, and fine particulate matter with diameter equal to or smaller than 2.5 µm (PM_2.5) on hospitalization for community-acquired pneumonia in older adults.

Methods: We used a population-based case–control study in Hamilton, Ontario, Canada. We enrolled 345 hospitalized patients aged 65 years or more for community-acquired pneumonia and 494 control participants, aged 65 years and more, randomly selected from the same community as cases from July 2003 to April 2005. Health data were collected by personal interview. Annual average levels of nitrogen dioxide, sulfur dioxide, and PM_2.5 before the study period were estimated at the residential addresses of participants by inverse distance weighting, bicubic splined and land use regression methods and merged with participants' health data.

Measurements and Main Results: Long-term exposure to higher levels of nitrogen dioxide and PM_2.5 was significantly associated with hospitalization for community-acquired pneumonia (odds ratio [OR], 2.30; 95% confidence interval [CI], 1.25 to 4.21; P = 0.007 and OR, 2.26; 95% CI, 1.20 to 4.24; P = 0.012, respectively, over the 5th–95th percentile range increase of exposure). Sulfur dioxide did not appear to have any association (OR, 0.97; 95% CI, 0.59 to 1.61; P = 0.918). Results were somewhat sensitive to the choice of methods used to estimate air pollutant levels at residential addresses, although all risks from nitrogen dioxide and PM_2.5 exposure were positive and generally significant.

Conclusions: In older adults, exposure to ambient nitrogen dioxide and PM_2.5 was associated with hospitalization for community-acquired pneumonia.

Key Words: air pollution • case-control study • fine particulate matter • nitrogen dioxide • sulfur dioxide

AT A GLANCE COMMENTARY Scientific Knowledge on the Subject There are sparse data on long-term effects of air pollution on pneumonia hospitalization in the elderly. Moreover, previous studies have focused on the effect of short-term increases in air pollution. What This Study Adds to the Field We found that long-term ambient levels of NO2 and fine particulate matter with diameter equal to or smaller than 2.5 µm (PM2.5) were independently associated with pneumonia hospitalization in older adults.

 

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