Objective To explore the association of particulate matter with medium aerodynamic diameter ≤ 10μm (PM10) in the atmosphere during dust events with the daily number of tracheitis outpatient visits.
Methods The medical records of all tracheitis outpatient visiting to 7 medium or large general hospitals from March 1st to May 31st of 2004 in Wuwei, Gansu Province were retrieved. The selected time period represented frequent typical sandstorm weather. With adjustments to long time trends, seasonal trends, meteorological variables, and calendar effect, the relative risks (RRs) of tracheitis outpatient visits during sandstorm weather were calculated by semi-parametric generalized additive Poisson regression model (GAM).
Results There were significant associations between the PM10 of dust events and the daily number of tracheitis outpatient visits with a lag of 2 days in both genders. The results of co-pollutant model and multi-pollutant model indicated the effects of both PM10 and SO2 on the daily number of tracheitis outpatient visits in males or females were decreased after adjusting for other pollutants, but the significant associations were retained. However, the effects of NO2 on the daily number of tracheitis outpatient visits were towards null after adjusting for PM10 or/and SO2. The RRs of daily tracheitis outpatient visits increased with the intensity of dust events:clean day < light contaminated day < blowing sands < dust storm.
Conclusion PM10 in dust events is positively associated with increasing tracheitis outpatient visits in both males and females with time lag in a dose-effect manner.
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