Long-term Exposure to Ambient Air Pollutants and Increased Risk of Pneumonia in the UK Biobank

Background Short-term exposure to air pollution has been linked to pneumonia risk. However, evidence on the long-term effects of air pollution on pneumonia morbidity is scarce and inconsistent. We investigated the associations of long-term air pollutant exposure with pneumonia and explored the potential interactions with smoking. Research Question Is long-term exposure to ambient air pollution associated with the risk of pneumonia, and does smoking modify the associations? Study Design and Methods We analyzed data in 445,473 participants without pneumonia within 1 year before baseline from the UK Biobank. Annual average concentrations of particulate matter (particulate matter with a diameter < 2.5 μm [PM2.5] and particulate matter with a diameter < 10 μm [PM10]), nitrogen dioxide (NO2), and nitrogen oxides (NOx) were estimated using land-use regression models. Cox proportional hazards models were used to assess the associations between air pollutants and pneumonia incidence. Potential interactions between air pollution and smoking were examined on both additive and multiplicative scales. Results The hazard ratios of pneumonia for each interquartile range increase in PM2.5, PM10, NO2, and NOx concentrations were 1.06 (95% CI, 1.04-1.08), 1.10 (95% CI, 1.08-1.12), 1.12 (95% CI, 1.10-1.15), and 1.06 (95% CI, 1.04-1.07), respectively. There were significant additive and multiplicative interactions between air pollution and smoking. Compared with individuals who had never smoked with low air pollution exposure, individuals who had ever smoked with high air pollution exposure had the highest pneumonia risk (PM2.5: hazard ratio [HR], 1.78; 95% CI, 1.67-1.90; PM10: HR, 1.94; 95% CI, 1.82-2.06; NO2: HR, 2.06; 95% CI, 1.93-2.21; NOx: HR, 1.88; 95% CI, 1.76-2.00). The associations between air pollutants and pneumonia risk persisted in participants exposed to air pollutants concentrations meeting the European Union limits. Interpretation Long-term exposure to air pollutants was associated with an increased risk of pneumonia, especially in individuals who smoke. Short-term exposure to air pollution has been linked to pneumonia risk. However, evidence on the long-term effects of air pollution on pneumonia morbidity is scarce and inconsistent. We investigated the associations of long-term air pollutant exposure with pneumonia and explored the potential interactions with smoking. Is long-term exposure to ambient air pollution associated with the risk of pneumonia, and does smoking modify the associations? We analyzed data in 445,473 participants without pneumonia within 1 year before baseline from the UK Biobank. Annual average concentrations of particulate matter (particulate matter with a diameter < 2.5 μm [PM2.5] and particulate matter with a diameter < 10 μm [PM10]), nitrogen dioxide (NO2), and nitrogen oxides (NOx) were estimated using land-use regression models. Cox proportional hazards models were used to assess the associations between air pollutants and pneumonia incidence. Potential interactions between air pollution and smoking were examined on both additive and multiplicative scales. The hazard ratios of pneumonia for each interquartile range increase in PM2.5, PM10, NO2, and NOx concentrations were 1.06 (95% CI, 1.04-1.08), 1.10 (95% CI, 1.08-1.12), 1.12 (95% CI, 1.10-1.15), and 1.06 (95% CI, 1.04-1.07), respectively. There were significant additive and multiplicative interactions between air pollution and smoking. Compared with individuals who had never smoked with low air pollution exposure, individuals who had ever smoked with high air pollution exposure had the highest pneumonia risk (PM2.5: hazard ratio [HR], 1.78; 95% CI, 1.67-1.90; PM10: HR, 1.94; 95% CI, 1.82-2.06; NO2: HR, 2.06; 95% CI, 1.93-2.21; NOx: HR, 1.88; 95% CI, 1.76-2.00). The associations between air pollutants and pneumonia risk persisted in participants exposed to air pollutants concentrations meeting the European Union limits. Long-term exposure to air pollutants was associated with an increased risk of pneumonia, especially in individuals who smoke. What Can Big Data Teach Us About Air Pollution and Pneumonia?CHESTVol. 164Issue 1PreviewIn this issue of CHEST, Wang et al1 present an analysis of participants in the UK Biobank, demonstrating that long-term exposure to air pollution is associated with an increased risk of pneumonia. Although the link between air pollution and lower respiratory tract infections is not a novel finding, most prior epidemiologic studies have focused on short-term pollutant exposures in the days or week before disease manifestation.2,3 Fewer studies have examined the chronic effects of pollutant exposure, in part because of the lack of cohorts with adequate data and sufficient statistical power to study this risk factor for a relatively rare outcome. Full-Text PDF