Ambient air pollution increases the risk of respiratory morbidity, but evidence concerning the effects of traffic-related air pollutants (TRAPs) on bronchitis admissions is scarce, and multi-city scale studies are needed. This study aimed to evaluate the associations of a set of TRAPs with bronchitis admission and to explore potential modifiers of the associations. Data on hospital admissions for bronchitis, air pollution, and meteorological factors from 1 January 2015 to 31 December 2021 were collected in 8 cities across Gansu Province, China. A generalized additive model (GAM) based on the Quasi-Poisson distribution, in combination with a distributed lag nonlinear model (DLNM), was used to evaluate the association between air pollutants and bronchitis admissions, controlling for calendar time (to control seasonality and long-term trend), meteorological factors (i.e., air temperature, relative humidity), and other possible confounders. We also performed a stratified analysis by gender, age, and season to assess potential effect modification within the study. Totally, 155,133 bronchitis patients were identified during the study period, including 2557 days. The daily number of hospital admissions for bronchitis ranged from 0 to 52. The results showed that exposure to PM2.5, PM10, NO2, and CO was positively correlated with an increased risk of hospital admission for bronchitis. Each 10 µg/m3 increase in PM2.5, PM10, NO2 was associated with a 3.2% (relative risk (RR) = 1.032, 95% confidence interval (CI): 1.020,1.045, lag 0–14 day), 13.5% (RR = 1.135, 95%CI: 1.103, 1.167, lag 0–11 day), and 9.5% (RR = 1.095, 95%CI: 1.081, 1.109, lag 0–14 day) increase in hospital admission for bronchitis, respectively. With a 1 mg/m3 increase in CO concentration, the risk of hospital admission for bronchitis increased by 7.7% (RR = 1.077, 95%CI: 1.047,1.108, lag 0–14 day). Subgroup analysis revealed that males and patients with bronchitis aged 0–14 years old were more sensitive to a change in PM2.5, PM10, NO2, and CO. Additionally, in the cold season, exposure to PM2.5, PM10, NO2, and CO was related to a significantly higher admission risk of bronchitis than in the warm season. In conclusion, exposure to PM2.5, PM10, NO2, and CO is associated with an increase in hospital admissions for bronchitis in 8 cities of Gansu, China. Our analyses present the first empirical evidence that prevailing air pollution levels in Gansu, China, are associated with increased incidence of bronchitis, underscoring the need to reinforce policies aimed at further reducing air pollution in the region. This study also highlights the critical importance of mitigating the detrimental effects of air pollution on respiratory health, particularly to safeguard at-risk populations.

Association between traffic-related air pollutants and bronchitis admissions: a time series study in 8 cities in Gansu Province, China

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2025年11月22日

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Shengcong Tao,
Jiyuan Dong

摘要

Ambient air pollution increases the risk of respiratory morbidity, but evidence concerning the effects of traffic-related air pollutants (TRAPs) on bronchitis admissions is scarce, and multi-city scale studies are needed. This study aimed to evaluate the associations of a set of TRAPs with bronchitis admission and to explore potential modifiers of the associations. Data on hospital admissions for bronchitis, air pollution, and meteorological factors from 1 January 2015 to 31 December 2021 were collected in 8 cities across Gansu Province, China. A generalized additive model (GAM) based on the Quasi-Poisson distribution, in combination with a distributed lag nonlinear model (DLNM), was used to evaluate the association between air pollutants and bronchitis admissions, controlling for calendar time (to control seasonality and long-term trend), meteorological factors (i.e., air temperature, relative humidity), and other possible confounders. We also performed a stratified analysis by gender, age, and season to assess potential effect modification within the study. Totally, 155,133 bronchitis patients were identified during the study period, including 2557 days. The daily number of hospital admissions for bronchitis ranged from 0 to 52. The results showed that exposure to PM_2.5, PM₁₀, NO₂, and CO was positively correlated with an increased risk of hospital admission for bronchitis. Each 10 µg/m³ increase in PM_2.5, PM₁₀, NO₂ was associated with a 3.2% (relative risk (RR) = 1.032, 95% confidence interval (CI): 1.020,1.045, lag 0–14 day), 13.5% (RR = 1.135, 95%CI: 1.103, 1.167, lag 0–11 day), and 9.5% (RR = 1.095, 95%CI: 1.081, 1.109, lag 0–14 day) increase in hospital admission for bronchitis, respectively. With a 1 mg/m³ increase in CO concentration, the risk of hospital admission for bronchitis increased by 7.7% (RR = 1.077, 95%CI: 1.047,1.108, lag 0–14 day). Subgroup analysis revealed that males and patients with bronchitis aged 0–14 years old were more sensitive to a change in PM_2.5, PM₁₀, NO₂, and CO. Additionally, in the cold season, exposure to PM_2.5, PM₁₀, NO₂, and CO was related to a significantly higher admission risk of bronchitis than in the warm season. In conclusion, exposure to PM_2.5, PM₁₀, NO₂, and CO is associated with an increase in hospital admissions for bronchitis in 8 cities of Gansu, China. Our analyses present the first empirical evidence that prevailing air pollution levels in Gansu, China, are associated with increased incidence of bronchitis, underscoring the need to reinforce policies aimed at further reducing air pollution in the region. This study also highlights the critical importance of mitigating the detrimental effects of air pollution on respiratory health, particularly to safeguard at-risk populations.