PEDIATRIC ASTHMA AND SAHARAN DUST IN THE WINDWARD ISLANDS IN THE CARIBBEAN

The annual seasonal intrusion of Saharan Dust across the Atlantic Ocean is well known and has been variably linked with asthma in the Caribbean islands. The PM₁₀ and PM_2.5 concentrations in the plumes often exceed the World Health Organization guidelines. A few of the small number of studies in the Caribbean have shown significant correlations between asthma and Saharan dust events (SDE), while other studies found none. The aim of this first multinational study is to determine if there is a consistent spatial and temporal correlation between the seasonal SDE and pediatric asthma in the Windward Islands in the Caribbean.

The study area includes four islands located between latitude 12⁰N and 16⁰N and longitude 60⁰ W and 62⁰W conducted between January 1, 2015 and December 31, 2017. The patient data was collected only after ethics approval from each of the islands and the University of Texas at Dallas. Dust events were determined from satellite data since none of the islands in the study area maintains ground-based dust monitoring stations. The dust data was obtained from the NASA’s Modern-Era Retrospective analysis for Research and Applications-Version 2 (MERRA-2). The advantage of MERRA-2 data was there were no temporal or spatial gaps and it and provided uniform coverage for the study area.

We found a total of ~6600 pediatric asthma emergency room visits over the study period. There was a clear seasonal variation in dust days over the three years. The SDE were determined for the region and differentiated from the non-dust days. Poisson statistical and other analysis were performed using R. There was a statistically significant correlation (p value < 0.001) between PM_2.5 and the emergency room visits for the region. This was most significant in 2015 but not in 2017. The SDE showed significant correlation only in 2016. Interestingly, the effects of PM_2.5 and PM₁₀ were statistically significant (p-value <0.001) on the Non-Saharan dust days in 2015 and 2017. These early results indicate inconsistent effects of the dust depending on the year and the region of study. Based on the known pathogenesis of asthma and the variable triggers, it is likely that both local factors such as viral infections, and possibly seasonal variations in the source location of the dust contribute to the variable correlations in pediatric asthma incidence.