Abstract
Background: Previous studies have revealed that meteorological factors or ambient air pollutants were associated with childhood asthma, but their interactive effects are scarcely known. Methods: In order to investigate the potential interactions between meteorological factors and air pollutants on childhood asthma, we obtained daily data on meteorological factors (mean temperature, mean relative humidity, and mean air pressure), air particulate matter (PM) with diameter < 2.5 µm (PM2.5) and < 10 µm (PM10), and outpatient visits for childhood asthma during 2007-2017 in Shanghai, China. Independent effects of meteorological factors and PM on childhood asthma were estimated using distributed lag non-linear model (DLNM), and then relative excess risk due to interaction (RERI) was calculated to assess their potential interactions. Results: A total of 976, 350 outpatient visits for childhood asthma were included in this study. Significant lagged and non-linear effects of meteorological factors and PM exposure on childhood asthma were observed in DLNM analyses. Further, in interaction analysis, we found statistically significant antagonistic interaction between mean temperature and PM (RERI: -0.14, 95%CI: -0.15, -0.12 for PM2.5; RERI: -0.09, 95%CI: -0.10, -0.08 for PM10) and synergistic interaction between mean air pressure and PM (RERI: 0.16, 95%CI: 0.14, 0.18 for PM2.5; RERI: 0.17, 95%CI: 0.15, 0.19 for PM10) on childhood asthma. Subgroup analyses by sex and age as well as sensitivity analyses of alternative degree of freedoms for calendar time, meteorological factors and PM are performed and confirmed the robustness of our results. Conclusion: Our findings provide supporting evidence that meteorological factors and PM might interactively affect childhood asthma, including antagonistic interaction between temperature and PM and synergistic interaction between air pressure and PM.
The temporal lagged association between meteorological factors and malaria in 30 counties in south-west China: a multilevel distributed lag non-linear analysis
