Associations between PM10 from Traffic, Resuspension, Sand Storms and Volcanic Sources and Asthma Drugs Dispensing

Abstract BackgroundParticle matter (PM) is detrimental to respiratory health, particularly in individuals with underlying respiratory disease, e.g. asthma. In the capital area of Iceland PM is both from anthropogenic sources, mainly traffic and local resuspension, as well as natural sources, such as dust-and volcanic ash storms. The aim was to study the association between all kinds of PM events from and daily dispensing of asthma drug as a proxy for respiratory health.Material and methodsThe study period was 2005-2015. Dispensing of asthma drugs for all individuals living in the capital area of Iceland were obtained from health registries. Concentrations of daily air pollution, pollen, and meteorological variables were obtained. Dust sources were determined for days when PM exceeded the health limit (24-hour mean 50 µg/m3) which are defined as “PM events”. The data were analysed using generalised non-linear models (GNM) methods and adjusted for both season and time trend. Results There were 137 PM event days where PM exceeded the health limit, and the source of the particles could be determined. The source of PM events was most often traffic (5%) or local resuspension 92(%), but PM events were also due to dust storms (1%) and volcanic ash (0.2%). During the 11 year study period there were on average 85 (standard deviation 45) daily dispensings of short-acting asthma drugs and 31 (19 standard deviations) dispensing of long-acting drugs. In the regression analysis, PM events from traffic and resuspension sources were associated with increases in the number of individuals who filled prescriptions for both long- and short-acting asthma drug in the following 7 days. Volcanic ash PM events were associated with dispensing of long-acting drugs, and short-acting drug use in summer and in individuals aged less than 18 years. DiscussionPM from traffic and local resuspension are the largest contributors to respiratory morbidity in Iceland’s capital area, although volcanic particles were also a significant contributor. PM from dust storms which did not originate from recent volcanic sources, was not associated with this indicator of poor respiratory health.