The Association between Respiratory Infection and Air Pollution in the Setting of Air Quality Policy and Economic Change

Abstract

Rationale: Fine particulate matter air pollution of 2.5 μm or less in diameter (PM_2.5) has been associated with an increased risk of respiratory disease, but assessments of specific respiratory infections in adults are lacking.

Objectives: To estimate the rate of respiratory infection healthcare encounters in adults associated with acute increases in PM_2.5 concentrations.

Methods: Using case-crossover methods, we studied 498,118 adult New York State residents with a primary diagnosis of influenza, bacterial pneumonia, or culture-negative pneumonia upon hospitalization or emergency department (ED) visit (2005-2016). We estimated the relative rate of healthcare encounters associated with increases in PM_2.5 in the previous 1-7 days and explored differences before (2005-2007), during (2008-2013), and after (2014-2016) implementation of air quality policies and economic changes.

Results: Interquartile range increases in PM_2.5 over the previous 7 days were associated with increased excess rates (ERs) of culture-negative pneumonia hospitalizations (2.5%; 95% confidence interval [CI], 1.7-3.2%) and ED visits (2.5%; 95% CI, 1.4-3.6%), and increased ERs of influenza ED visits (3.9%; 95% CI, 2.1-5.6%). Bacterial pneumonia hospitalizations, but not ED visits, were associated with increases in PM_2.5 and, though imprecise, were of a similar magnitude to culture-negative pneumonia (Lag Day 6 ER, 2.3%; 95% CI, 0.3-4.3). Increased relative rates of influenza ED visits and culture-negative pneumonia hospitalizations were generally larger in the "after" period (P < 0.025 for both outcomes), compared with the "during" period, despite reductions in overall PM_2.5 concentrations.

Conclusions: Increased rates of culture-negative pneumonia and influenza were associated with increased PM_2.5 concentrations during the previous week, which persisted despite reductions in PM_2.5 from air quality policies and economic changes. Though unexplained, this temporal variation may reflect altered toxicity of different PM_2.5 mixtures or increased pathogen virulence.

Keywords: air pollution; bacterial pneumonia; influenza virus; particulate matter.

Figure 1.

Distribution of fine particulate matter air pollution of 2.5 μm or less in diameter (PM_2.5) concentrations (μg/m³) for case periods by study site and time period.

Figure 2.

Excess rate (and 95% confidence interval [CI]) of infectious disease hospitalizations and emergency department visits associated with each interquartile range increase in concentration of fine particulate matter air pollution of 2.5 μm or less in diameter, by infection and lag day mean.

Figure 3.

Excess rate (and 95% confidence interval [CI]) of hospitalizations and emergency department visits for culture-negative pneumonia and influenza associated with each interquartile range increase in concentration of fine particulate matter air pollution of 2.5 μm or less in diameter for the 0- to 2-day lag time by period.