Estimation of the effects of heavy Asian dust on respiratory function by definition type

Abstract Background The adverse effects of Asian dust (AD) on health have been demonstrated in earlier studies, but there is no standardized definition for heavy–AD. This study aimed to examine which definition of heavy–AD has the most adverse effect on respiratory function. Methods One–hundred–and–thirty–seven adults with asthma, and 384 school children self-measured their morning peak expiratory flow (PEF). The four definitions of heavy–AD are: (1) the definition provided by the Japan Meteorological Agency (JMA), (2) daily median AD particle level ≥ 0.07 km−1, obtained through light detection and ranging (LIDAR) (3) hourly AD particle level ≥ 0.1 km−1, and (4) hourly level ≥ 0.07 km−1. Linear mixed models were used to estimate the effects of heavy–AD, by definition type, on daily PEF values. Results In adults with asthma, as per the JMA’s definition, significantly reduced PEF were observed on heavy–AD days (lag 0), lag 0–1, and lag 0–3. In school children, after a heavy–AD event, as defined by the JMA, PEF significantly decreased on lag 0–1, lag 0–2, and lag 0–3. However, as per the other definitions, there was no significant decrease in the PEF in the adults and children. Conclusion The associations between heavy–AD and respiratory function differed between these definitions