Hourly concentrations of fine and coarse particulate matter and dynamic pulmonary function measurements among 4992 adult asthmatic patients in 25 Chinese cities.

The short-term associations of fine particulate matter (PM2.5) and coarse particulate matter (PM2.5-10) with pulmonary function were inconsistent and rarely evaluated by dynamic measurements. Our study aimed to investigate the associations of PM2.5 and PM2.5-10 with real-time pulmonary function. We conducted a longitudinal study based on dynamic pulmonary function measurements among adult asthmatic patients in 25 cities of 19 provincial regions of China from 2017 to 2020. Linear mixed-effects models combined with polynomial distributed lag models were used for statistical analysis. A total of 298,396 records among 4,992 asthmatic patients were evaluated. We found generally inverse associations of PM2.5 and PM2.5-10 with 16 pulmonary function indicators that were independent of gaseous pollutants. The associations occurred at lag 1 d, became the strongest at lag 4 d, and vanished a week later. PM2.5-10 had stronger associations than PM2.5, especially in southern China. Nationally, an interquartile increase in PM2.5-10 (28.0 μg/m3) was significantly associated with decreases in forced expiratory volume in 1 s (FEV1, 41.6 mL), the ratio of FEV1 in forced vital capacity (1.1%), peak expiratory flow (136.9 mL/s), and forced expiratory flow at 25-75% of forced vital capacity (54.3 mL/s). We observed stronger associations in patients of male, BMI ≥ 25 kg/m2, age ≥ 45 years old, and during warm seasons. In conclusion, this study provided robust evidence for impaired pulmonary function by short-term exposure to PM2.5 and PM2.5-10 in asthmatic patients using the largest dataset of dynamic monitoring. The associations can last for one week and PM2.5-10 may be more hazardous.