Long-term exposure to ambient air pollution ups risk of pneumonia

Individuals with long-term exposure to air pollutants appear to be at higher risk of pneumonia, with the risk being more pronounced among smokers, as shown in a study.

The study used data from the UK Biobank and included 445,473 participants who were free of pneumonia within 1 year before baseline.

Researchers applied land-use regression models to estimate the annual average concentrations of particulate matter (PM_2.5 and PM₁₀), nitrogen dioxide (NO₂), and nitrogen oxides (NO_x). They also performed Cox proportional hazards analysis to examine the associations between air pollutants and pneumonia incidence.

Exposure to ambient air pollution was associated with increased risk of developing pneumonia. The risk increased by 6–12 percent for every interquartile range increase in PM_2.5 (hazard ratio [HR], 1.06, 95 percent confidence interval [CI], 1.04–1.08), PM₁₀ (HR, 1.10, 95 percent CI, 1.08–1.12), NO₂ (HR, 1.12, 95 percent CI, 1.10–1.15), and NO_x (HR, 1.06, 95 percent CI, 1.04–1.07) concentrations.

Significant additive and multiplicative interactions were seen between air pollution and smoking. Relative to never smokers with low air pollution exposure, ever smokers with high air pollution exposure had the highest pneumonia risk (PM_2.5: HR, 1.78, 95 percent CI, 1.67–1.90; PM₁₀: HR, 1.94, 95 percent CI, 1.82–2.06; NO₂: HR, 2.06, 95 percent CI, 1.93–2.21; NO_x: HR, 1.88, 95 percent CI, 1.76–2.00).

The pneumonia risk associated with air pollutants remained increased in participants exposed to air pollutant concentrations meeting the European Union limits.