Independent effects of traffic, sandstorm and volcanic particles on emergency hospital visits in Reykjavík, Iceland?

Abstract

Background After the spring 2010 Eyjafjallajökull volcanic eruption volcanic ash contributed to particulate matter (PM) levels in Iceland. Aims The aim of the present study was to analyze the association between sources of high PM levels and emergency hospital visits in the capital area. Materials and methods The outcomes were acute admissions and emergency department visits for cardiopulmonary, stroke and respiratory causes to Landspitali University Hospital in Reykjavík (pop. 200.000) from 2007 to 2010. Air pollution data and the estimated source of particles of each event where the PM10 health limit (50 µg/m3) was exceeded were obtained from authorities. The data were analyzed using generalized additive regression, with indicator variables for each particle source (traffic, sandstorms, or volcanic ash) the current and two previous days (lag02), adjusted for other pollutants, weather and time trend. Results During the study period the average number daily emergency hospital visits was 10.5. High PM10 levels occurred 91 days, the source was traffic 37 days, sandstorms 11 days, and volcanic ash 9 days. In preliminary analysis, we found that each day with high PM10 levels from traffic were associated with an increase in the number of emergency hospital visits of 9% (95% confidence interval (CI) 1-17%), adjusting for other pollutants and weather. High PM levels due to sandstorms and volcanic ash were not significantly associated with emergency hospital visits when adjusting for other pollutants. In unadjusted models, high PM10 levels due to sandstorms and volcanic ash were nearly significantly (p<0.10) associated with emergency hospital visits, increasing 13% (95% CI 0-27%) for volcanic ash and 9% (95% CI -1-21%) for sandstorms. Conclusion In this study of particle sources we identified independent effects of particles originating in traffic, and near-significant effects of volcanic dust and sandstorms.