Measuring the acute health effects of dust storms: A matched case-control series

Background and Objectives: Transcontinental sandstorms are frequent in the eastern Mediterranean basin, with southeasterly winds transporting dust from the Sahara desert. The resulting ambient particulate matter is a potential health hazard for exposed populations. We aimed to quantify the extent of acute cardio-respiratory health effects attributable to sandstorms in an Eastern Mediterranean region.

Methods: Continuous air quality monitoring is carried out by the Israel Ministry of Environmental Protection. We identified all sandstorm days (SSDs) for the period between January 2006 and December 2008. For each of these "case" days, we selected 2 non-sandstorm control days from the previous and the subsequent fortnights, matching them for day of the week. The number of emergency department (ED) visits for acute cardio-respiratory conditions at a regional medical center (Barzilai Medical Center) was counted for each SSD for and its matched control days. SSD counts were compared to mean matched counts using the paired t-test.

Results: 48 SSDs and 96 matched control days were identified during the 3-year study period. Mean cardio-respiratory patient load on SSDs was 23.23±9.8 visits, compared to 21.15±8.14 on matched control days (p=0.017). This represents a relative increase of 9.8% over the expected patient load. In absolute terms, and based on the medical center's estimated catchment population, this represents an increase of approximately 1 ED visit per 100,000 for one SSD, translating to about 70 ED visits in the country.

Conclusion: While sandstorms are a detectable risk factor for acute cardio-respiratory syndromes, the de-facto impact of exposure in our area appears to be low. This finding may an indirect indicator of the effectiveness of the Ministry of Environmental Protection's pre-storm warning system, which appeals through the mass media to predisposed persons to remain indoors on SSDs.