Saharan Dust On T&T’s Doorstep, Forecast To Linger Into June

The passage of 2021’s first tropical wave for the Atlantic Hurricane Season improved air quality across T&T briefly over the last 24 hours. However, Saharan Dust concentrations are on the rise, with significant levels of dust forecast to remain across T&T through the next 7 to 10 days.

Air quality levels may dip to moderate levels with lowest visibility at 7-8 kilometers.

The Environmental Management Agency (EMA) air quality monitoring stations are recording AQI values at levels that are good to moderate in 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.

The Saharan Dust Forecast

Over the next 24 hours, Saharan Dust concentrations are forecast to gradually increase. Air quality levels will fluctuate between good to moderate. With the next surge of dust arriving on Monday, air quality may dip further to levels that are moderate to unhealthy for sensitive groups.

Through the week, air quality levels will fluctuate between moderate to unhealthy for sensitive groups.

On days with peak concentrations, visibility may be reduced between 7-10 kilometers.

12Z 23rd May 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 next week or so, with moderate to high 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 Monday 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 due to increased dust. 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 the ITCZ and tropical waves may shield Trinidad and Tobago from the Saharan Dust events. While tropical waves play a notable role in moving dust across the Atlantic and the Eastern Caribbean, these periodic tropical waves also improve air quality.

The concentration of the dust that follows the wave depends on the strength of the wave as it moves off the West African Coast. This is because of stronger thunderstorms across Central Africa. As strong winds move downward and outward from these thunderstorms, the wind kicks up dust as it moves across parts of the Saharan Desert and transports it into the upper atmosphere. This “plume” of dust follows the axis of the wave as it progresses westward into the Atlantic.

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.

Larger, more concentrated plumes of Saharan dust begin to occur in April and continue through November.

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