More Saharan Dust Surges For T&T, Windward Islands

As forecast, high concentrations of Saharan Dust arrived across T&T last weekend, with elevated dust levels persisting through this week. Unfortunately, more surges of dust are forecast to arrive across T&T later this week, with peak concentrations forecast to begin on Saturday 27th February 2021.

The Environmental Management Agency (EMA) air quality monitoring stations are recording AQI values at levels that are good to moderate in Trinidad and Tobago as of Saturday night. 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.

The Saharan Dust Forecast

Through Friday, lingering moderate concentrations of dust will remain present across T&T. The air quality will generally be at moderate levels, though it may improve to good levels in areas where showers occur.

From Saturday morning through Sunday afternoon, a rapid increase in dust concentrations is forecast with skies becoming increasingly hazy. Air quality levels are forecast to decrease to unhealthy for sensitive groups during this period.

Due to a favorable position of a high-pressure system, as quickly as the dust arrived, it will recede briefly on Monday 1st March 2021, with a new dust surge arriving early on Tuesday 2nd March 2021. Air quality may dip to levels that are moderate from Tuesday through much of next week.

00Z Friday 19th February 2021, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust.

What does this mean for you?

For the general population through the week (and through next week, with moderate Saharan dust concentrations forecast, little to no impacts are forecast beyond hazy skies. For sensitive groups, such as children, the elderly, and persons who suffer from respiratory ailments and allergies, you may need to avoid prolonged exertion outdoors.

Beginning Saturday morning, with high concentrations of Saharan Dust forecast, members of sensitive groups may experience health effects. The general public is not likely to be affected though visibility will be reduced. 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, and the Intertropical Convergence Zone (ITCZ) 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 and affect the Eastern Caribbean.

These Saharan Dust outbreaks tend to be milder in the Eastern Caribbean than the dust outbreaks associated with West African thunderstorms driving dust into the upper atmosphere from April through November.

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