Short-term air pollution exposure and risk of respiratory pathogen infections: an 11-year case-crossover study in Guangzhou, China

Background Limited epidemiological evidence exists on the relationship between short-term exposure to air pollutants and respiratory pathogen infections. This study investigates the association between short-term air pollution exposure and respiratory pathogen infections in Guangzhou, southern China. Methods A time-stratified case-crossover study design was applied. Data from 96,927 patients with suspected respiratory pathogen infections between 2013 and 2023 were collected. The daily air pollutant concentration is obtained from the local environmental monitoring station. Logistic regression was used to assess the effect of air pollutant exposure included in the equation on the risk of respiratory pathogen infection. Generalized additive models were used to analyze the relationship between pollutant exposure and hospital visits, adjusting for potential confounders such as temperature and precipitation. Sub-group analysis was performed to estimate the reliability of the correlations among the subgroups. Results The logistic regression model shows that PM2.5, NO2 and CO are included in the variable equation. Single-pollutant models indicate that there is a significant association between short-term exposure to NO2 and CO and an increased risk of hospital visits for respiratory infections, especially on lag day 0, while PM2.5 shows a non-linear relationship. In the multi-pollutant model, for each unit increase in NO2, the risk of hospital visits increased by 11.66%, and for CO, the risk increased by 0.64%. Subgroup analysis showed the effects were more pronounced in minors (< 18 years), while no significant gender differences were observed. Additionally, CO and NO2 interacted with PM2.5, amplifying the risk of infection. Conclusion This large-scale epidemiological study demonstrates significant associations between short-term air pollutant exposure and respiratory infections, particularly highlighting the risks of NO2 and CO exposure. The findings underscore the critical need for strengthening air quality monitoring and protection strategies in rapidly urbanizing regions, with special attention to vulnerable populations such as minors. These results provide evidence-based support for enhancing environmental health policies in metropolitan areas to better protect public health through improved air quality standards and early warning systems.