Associations of air pollutants with pneumonia hospital admissions in Qingdao, China: a prospective cohort study.

Studies about the pneumonia morbidity effects of various air pollution exposure are still limited in China. We aimed to explore the short-term effect of air pollutants exposure on pneumonia admission and identify the vulnerable groups in Qingdao, China. From January 2015 to October 2017, a prospective cohort involving 433,032 participants across 3 counties in Qingdao were enrolled in the study. Distributed lag nonlinear model (DLNM) was applied to assess the associations between air pollutants and pneumonia hospitalizations. There were 636 cases of pneumonia, with an annual incidence density of 54.33 per 100,000 person-years (95% CI: 50.11, 58.56). A 10 μg/m increment of sulfur dioxide (SO) distributed at a 4-week lag in Qingdao was associated with increased pneumonia hospitalizations, with a risk ratio of 2.10 (95% CI: 1.06, 4.13). Subgroup analyses indicate that PM ≤ 2.5 μm in aerodynamic diameter and SO showed stronger effects on pneumonia in females than males, whereas people in urban regions were more vulnerable to nitrogen dioxide and ozone (O) than the others. We also observed distinct acute effects and harvesting effects of SO and O on pneumonia in urban areas. Strategies should be taken to further reduce levels of ambient PM, SO, and O.