Significant Concentrations of Saharan Dust Across T&T Into Next Week

A significant surge of Saharan Dust arrived across Trinidad and Tobago overnight Monday into Tuesday, with at least 2-3 more surges forecast over the next week.

On Tuesday afternoon the Environmental Management Agency (EMA) air quality monitoring stations are recording AQI values at levels that are moderate to unhealthy for sensitive groups across Trinidad and Tobago. These measurements are based on PM2.5 (particulates the size of 2.5 micrometers and smaller, usually associated with increases in Saharan Dust, vehicle exhaust, and smoke) and PM10 particulates. Across the Lesser Antilles, mainly islands south of the French Antilles are experiencing degraded air quality.

A map showing the different air quality indices across the Lesser Antilles as Saharan Dust affects the region, Trinidad and Tobago is orange, indicating air quality unhealthy for sensitive groups. Islands between Grenada to Martinique are in yellow, indicating moderate air quality. All other islands and countries are in green, indicating good air quality.
Air quality index across the Lesser Antilles

The Saharan Dust Forecast

Over the next seven to ten days, the air quality will fluctuate between levels that are moderate to unhealthy for sensitive groups.

A high-pressure system dominating, across the Atlantic, is producing strong easterly trade winds. These winds have become a conveyor belt for a significant and prolonged surge of Saharan Dust into mid-April.

00Z Wednesday 6th April 2021, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust moving off the African coast, periodically making its way across Trinidad, Tobago and the Lesser Antilles.
00ZTuesday 6th April 2021, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust.

What does this mean for you?

Members of sensitive groups may experience health effects. The general public is not likely to be affected. There is an increasing likelihood of respiratory symptoms in sensitive individuals, aggravation of heart or lung disease, and premature mortality in persons with cardiopulmonary disease & the elderly.

We’re in a period where a ridge of high pressure stays over the central Sahara Desert. The Intertropical Convergence Zone (ITCZ) also remains over the Gulf of Guinea.

The Harmattan wind accelerates when it blows across the mountain massifs of Northwest Africa. If its speed is high enough and it blows over dust source regions, it lifts the dust and disperses it.

Dust that makes it into the upper levels of the atmosphere can then get transported across the Atlantic Ocean. The plumes of dust eventually affect the Eastern Caribbean.

Saharan Dust outbreaks from December through early April tend to be milder in the Eastern Caribbean compared to late April through November. During the latter period, those dust outbreaks are associated with West African thunderstorms driving dust into the upper atmosphere.

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