Air pollution and hospital admissions for pneumonia: Are there potentially sensitive groups?

Abstract

Recent studies have shown that air pollution is a risk factor for hospitalization for pneumonia. However, there is limited evidence to suggest what subpopulations are at greater risk from air pollution. This study was undertaken to examine the modifying effect of specific secondary diagnosis (including hypertension, diabetes, asthma, and upper respiratory infections) on the relationship between hospital admissions for pneumonia and ambient air pollutants. Hospital admissions for pneumonia and ambient air pollution data for Kaohsiung were obtained for the period 1996–2006. The relative risk of hospital admission was estimated using a case-crossover approach. We found that an interquartile range (IQR) increase in PM₁₀, NO₂, and CO on warm days was associated with a 28% (95% confidence interval [CI], 11–48%), 40% (95% CI, 20–63%), and 31% (95% CI, 19–45%), respectively, increase in admissions for pneumonia with upper respiratory infections (URI), but only 23% (95% CI, 18–28%), 30% (95% CI, 25–36%), and 24% (95% CI, 21–28%), respectively, increase for persons without URI. An IQR increase in PM₁₀, SO₂, and CO on cool days was associated with a 70% (95% CI, 50–92%), 30% (95% CI, 15–47%), and 64% (95% CI, 47–83%), respectively, increase in admissions in persons with URI, and an increase of 64% (95% CI, 57–70%), 18% (95% CI, 14–22%), and 55% (95% CI, 50–60%), respectively, in admissions in persons without URI. Our findings provide evidence that patients with comorbid URI may increase the risk of hospital admissions for pneumonia, in relation to air pollutant levels.

Keywords::

• Air pollution
• case-crossover
• hospital admissions
• pneumonia
• sensitive population

Declaration of interest: This study was partly supported by a grant from the National Science Council, Executive Yuan, Taiwan (NSC-95-2314-B-037-070-MY2). This study is based in part on data from the National Insurance Research Database provided by the Bureau of National Health Insurance, Department of Health, and managed by National Health Research Institutes. The interpretation and conclusions contained herein do not represent those of Bureau of National Health Insurance, Department of Health, or National Health Research Institutes. The authors alone are responsible for the content and writing of the paper.