Association of short-term exposure to PM 1 with hospital admission from total and cause-specific respiratory diseases

Evidence of short-term exposure to particulate matter with an aerodynamic diameter ≤1 μm (PM ) on hospital admission for respiratory diseases (RDs) is limited. We aimed to estimate the associated risk of PM on hospital admissions for RDs. In this time-stratified case-crossover study, we assigned cases who had been admitted to hospital for RDs in Guangdong, China between 2016 and 2019. Exposure to PM was assigned on the basis of the patient's residence for each case day and its control days. Conditional logistic regression models and distributed lag nonlinear models were used to quantify the association of PM exposure with hospital admission for RDs at lag 0-1 days. A total of 408, 658 hospital admissions for total RDs were recorded in the study period. Each 10 μg/m increase in PM was significantly associated with a 1.39% (95% confidence interval [CI]: 0.87%-1.91%), 1.97% (95% CI: 1.06%-2.87%) and 1.69% (95% CI: 0.67%-2.71%) increase in odds of hospital admissions for total RDs, chronic obstructive pulmonary disease (COPD) and pneumonia. The excess fraction of hospital admission for total RDs attributable to PM exposure was 6.03%, while 6.59% for COPD and 7.48% for pneumonia. Besides, higher excess fractions were more pronounced for hospital admission of total RDs in older patients (>75 years). Our results support that PM is associated with increased risks of hospital admissions for RDs. It emphasizes the needs to pay attention to the effects of PM on respiratory health, especially among elderly patients.