The effect of air pollution on the risk of hospitalization for H1N1 influenza based on GAM and DLNM models

Abstract Background With the rapid advancement of industrialization and urbanization, air pollution is becoming increasingly serious, posing a huge threat to human health. There is ambiguity in the research on the impact of air pollutants on the severity of influenza. Therefore, exploring the link between air pollution and the risk of hospitalization for Influenza A (H1N1) is of great significance. Methods A 9-year time series data was collected from Luoyang from 2014 to 2022 to investigate the impact of air pollutants (PM2.5, PM10, SO2, NO2, O3, and CO) on the risk of hospitalization for H1N1 influenza. Generalized additive model (GAM) and Distributed Lag Nonlinear Model(DLNM) based on Poisson regression were established and population stratification analysis was used to explore the differences in the population by gender, age, place of residence, and season. Results There were 363,339 hospital admissions for H1N1 influenza in Luoyang from January 1, 2014 to November 4th, 2022. Among them, there are 199,800 female (54.99%), 163,539 male(45.01%); There are different lag effects of six air pollutants on the hospitalization of patients with H1N1 influenza, and patients showed a non-linear increasing trend with the increase of pollutants concentration. For every 10 µg/m3 increase in PM2.5, PM10, O3 and SO2 concentrations (1 mg/m3 increase in CO), the excess risk (ER) in hospitalizations increased by 0.532% (95% CI: 0.400% -0.663%), 1.039% (95% CI: 0.897% -1.181%), 1.025% (95% CI: 0.758% -1.292%), 1.982% (95% CI: 0.48% -3.506%) and 4.815% (95% CI: 3.480% -6.168%), respectively. The stratified analysis results show that male, age < 18 years old, and urban populations may be more sensitive to pollutants, especially in Summer. Conclusions This time-series study suggests that short-term exposure to air pollution may increase the risk of hospitalization for H1N1 influenza. As the concentration of pollutants increases, the risk of hospitalization for H1N1 influenza exhibit a non-linear increasing trend. These findings have important implications for policymakers to take concrete actions to reduce atmospheric pollution concentrations and protect the environment.