Associations of ambient fine particulate matter with lung function and nasal microbiota: A panel study in asthmatic...

Fine particulate matter (PM_2.5) has been associated with an increased risk of asthma. However, the underlying mechanisms through which PM_2.5 affects respiratory health in children with asthma remain poorly understood. To address this gap, we performed a panel study to investigate the associations of short-term PM_2.5 exposure with lung function and nasal microbiota in asthmatic children. The study included 50 school-aged asthmatic children, who underwent repeated examinations every three months, including lung function testing and nasal swab sample collection. Linear mixed-effect models and the linear discriminant analysis effect size were adopted to evaluate the impacts of PM_2.5 on lung function and nasal microbiota. Based on 160 lung function records and 160 nasal samples, we found that per interquartile range increase in PM_2.5 concentration at lag 0-72 h was associated with a decrease of 0.09 L (95 % CI: 0.01, 0.16), 0.30 L/s (95 CI: 0.04, 0.57), 0.18 L/s (95 % CI: 0.03, 0.33), and 0.30 L/s (95 % CI: 0.07, 0.53) in forced expiratory volume in 1 s, forced expiratory flow at 50 % and 75 % of forced vital capacity, and the maximal mid-expiratory flow, respectively. Additionally, short-term exposure to PM_2.5 was also associated with decreased Chao 1 and Simpson's index, decreased relative abundance in Corynebacterium and Staphylococcus, and increased relative abundance in Muribaculaceae, Ralstonia, and Moraxella. In conclusion, our study demonstrated that short-term exposure to PM_2.5 may impair small airway function, reduce nasal microbiota evenness, and induce microbiota dysbiosis in asthmatic children.