The effect of air pollutants on COPD-hospitalized patients in Lanzhou, China (2015-2019).

Background: Lanzhou is the largest heavy industrial city in northwest China and it is a typical geographical valley-like city. However, there are few studies on the relationship between air pollutants and COPD, and their respective sample sizes are small, resulting in inconsistent results. The aim of this study is to analyze the effects of air pollutants on COPD hospitalizations in Lanzhou, China.

Methods: An ecological time series study with distributed lag non-linear model (DLNM) was used for analysis. Daily COPD hospitalization data in Lanzhou from 1 January 2015 to 31 December 2019 were collected from 25 hospitals, as well as air pollutant data and meteorological data.

Results: A total of 18,275 COPD hospitalizations were enrolled. For 10 μg/m³ increase in PM_2.5, PM₁₀, SO₂, NO₂, and 1 mg/m³ increase in CO at lag 07 day, the RR95%CI of COPD hospitalizations were 1.048 (1.030, 1.067), 1.008 (1.004, 1.013), 1.091 (1.048, 1.135), 1.043 (1.018, 1.068), and 1.160 (1.084, 1.242), respectively. The exposure-response curves between air pollutants (except O3-8h) and COPD hospitalizations were approximately linear with no thresholds. Female, and the harmful effect of PM on aged <65 years, the effect of gaseous pollutant on those aged ≥65 years, were stronger, particularly in the cold season. Exposure to air pollutants (except O_3-8h) might increase the risk of COPD hospitalizations. O_3-8h has a weak and unstable effect on COPD.

Conclusion: Exposure to air pollutants (except O_3-8h) increases the risk of COPD hospitalizations. O_3-8h has a weak and unstable effect on COPD hospital admissions. The harmful effect of gaseous pollutants (except O_3-8h) on COPD-hospitalized patients was stronger than that of PM.