Short-Term Exposure to Ambient Air Pollution and Asthma Mortality.

Rationale: Short-term exposure to air pollution has been associated with asthma exacerbation and increased healthcare use caused by asthma, but its effect on asthma mortality remains largely unknown. Objectives: To quantitatively assess the association between short-term exposure to air pollution and asthma mortality. Methods: We investigated 4,454 individuals who lived in Hubei province, China, and died from asthma between 2013 and 2018. A case-crossover design and conditional logistic regression models were applied for data analyses. Exposures to particulate matter ≤2.5 μm in aerodynamic diameter (PM2.5 ), particulate matter ≤10 μm in aerodynamic diameter (PM10 ), sulfur dioxide (SO2 ), nitrogen dioxide (NO2 ), carbon monoxide (CO), and ozone (O3 ) were estimated by inverse distance weighted averages of all monitoring stations within 50 km from each case's home address. Measurements and Main Results: Each interquartile range (IQR) increase of PM2.5 (lag 3; IQR, 47.1 μg/m3 ), NO2 (lag 03; IQR, 26.3 μg/m3 ), and O3 (lag 3; IQR, 52.9 μg/m3 ) were positively associated with asthma mortality, with odds ratios of 1.07 (95% confidence interval, 1.01-1.12), 1.11 (95% confidence interval, 1.01-1.22), and 1.09 (95% confidence interval, 1.01-1.18), respectively. There was no evidence of departure from linearity for these associations. Further adjustment for other pollutants did not change the associations materially. We did not observe significant associations between PM10 , SO2 , and CO exposures and asthma mortality. Overall, the estimates remained consistent in various sensitivity analyses. Conclusions: Our results provide new evidence that short-term exposures to PM2.5 , NO2 , and O3 may increase asthma mortality risk. Further studies are needed to confirm our findings in other populations.