SAHARAN DUST AND PEDIATRIC ASTHMA: A MULTINATIONAL, MULTIYEAR ASSESSMENT IN THE CARIBBEAN

Background: The annual seasonal intrusion of Saharan Dust to the Caribbean has been linked with asthma, a complex disease and a major cause of morbidity. This first multinational, multiyear epidemiologic study examines the risk of asthma emergency room (ER) visits on Saharan dust days (SDDs) in the Caribbean. Saharan dust is the main source of aerosol pollution in the Caribbean and its composition is determined by the mineral dust source and the interactions with pollutants including anthropogenic aerosols such as black carbon, picked up during transport.

Methods: We examined the associations between SDDs and asthma ER visits on four islands (Dominica, St. Lucia, St. Vincent and Grenada) from January 2015 to December 2017, among children between the ages of 1 and 15 years old. Particulate exposure was estimated using bias-corrected MERRA-2 satellite-based PM_2.5, PM₁₀ data and the total black and organic carbon components (TCC). SDDs were defined by days that occurred only during the dust season with PM₁₀ exceeding 35 µg/m³ (SDD₁₀) or PM_2.5 exceeding 11µg/m³ (SDD_2.5). Time-stratified case-crossover multivariate regression analysis with distributed lags constrained via spline smoothing was used.

Results: Records in this study describes a total of 6353 asthma ER visits. There was a 9% (95% CI: 1,18%) increased average (over lags 0-6 days) regional (over all islands) risk of asthma ER visits on SDD_2.5 but no significant association with SDD₁₀. There was an increased average regional risk in 2016 with exposure to SDD_2.5 (12%, CI: 3,22%). Among the islands, Grenada had an increased average risk with SDD_2.5 (13%, CI: 4,24%), and similarly St. Lucia (11%, CI:1,22%). Grenada also the highest TCC among the islands and St. Lucia the highest levels of local urban anthropogenic PM₁₀.

Conclusion: SDD_2.5 concentrations were positively associated with pediatric asthma ER visits suggesting that in the Caribbean there is an increased risk from Saharan dust, but the association is complex. Differing results between individual islands and years may be partially attributable to differing anthropogenic sources and other confounding factors. This correlation should strengthen commitment in the region to warn and shelter vulnerable populations during SDDs, and bodes ill if Sahara dust transport and local urban development increase.