Short-term PM and PM exposure and asthma mortality in Jiangsu Province, China: What's the role of neighborhood characteristics?

BACKGROUND

Evidence suggests that particulate matter (PM) with smaller particle sizes (such as PM, PM with an aerodynamic diameter≤1 µm) may have more toxic health effects. However, the short-term association between PM and asthma mortality remains largely unknown.

OBJECTIVE

This study aimed to examine the short-term effects of PM and PM on asthma mortality, as well as to investigate how neighborhood characteristics modified this association.

METHODS

Daily data on asthma mortality were collected from 13 cities in Jiangsu Province, China, between 2016 and 2017. A time-stratified case-crossover design was attempted to examine the short-term effects of PM and PM on asthma mortality. Individual exposure levels of PM and PM on case and control days were determined based on individual's residential addresses. Stratified analyses by neighborhood characteristics (including green space, tree canopy, blue space, population density, nighttime light and street connectivity) were conducted to identify vulnerable living environments.

RESULTS

Mean daily concentrations of PM and PM on case days were 33.8 μg/m and 54.3 μg/m. Each 10 μg/m increase in three-day-averaged (lag02) PM and PM concentrations were associated with an increase of 6.66% (95%CI:1.18%,12.44%) and 2.39% (95%CI: 0.05%-4.78%) asthma mortality, respectively. Concentration-response curves showed a consistent increase in daily asthma mortality with increasing PM and PM concentrations. Subgroup analyses indicated that the effect of PM appeared to be evident in neighborhood characteristics with high green space, low urbanization level and poor street connectivity.

CONCLUSION

This study suggested an association between short-term PM and PM exposures and asthma mortality. Several neighborhood characteristics (such as green space and physical supportive environment) that could modify the effect of PM on asthma mortality should be further explored.