Concentrations of Saharan Dust are forecast to increase across the region, even with passages of multiple tropical waves over the next 5-7 days. The most significant surge is forecast to arrive across the region late Thursday into Friday, significantly reducing air quality and visibility into the weekend.
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.
Visibility across both islands remain at 10 kilometers and above.
The Saharan Dust Forecast
Following the passage of last week’s tropical wave, Saharan Dust has gradually increased across Trinidad and Tobago. This increase is short-lived as another weak tropical wave is forecast to move across T&T on Monday into early Tuesday, improving air quality.
Another surge is forecast on Tuesday, with concentrations increasing throughout the day until another weak tropical wave moves across the islands Wednesday into Thursday. However, high concentrations will remain across the region. Rainfall may briefly improve air quality in localized areas.
A significant surge of Saharan Dust is forecast to arrive across T&T and the Lesser Antilles on Thursday, with the peak concentrations, forecast Thursday into Friday. High to significant concentrations are forecast through the middle of the month, even with another weak tropical wave forecast to move across the region from June 13th into June 14th.
Air quality levels will fluctuate between good to moderate during tropical wave passages. By June 12th,, air quality may dip further to levels that are moderate to unhealthy for sensitive groups. On days with peak concentrations, visibility may be reduced between 7-10 kilometers.
What does this mean for you?
For the general population, 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.
From June 12th, with significant 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.