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.