Dust season changing as plumes arrive sooner – forecasters

More Saharan dust haze is expected across Barbados and the wider Caribbean in the coming weeks, with meteorologists warning that significant dust episodes are arriving earlier in the year and monitoring showing sustained high levels of dust transport across the Atlantic.

Many Barbadians endured a disruptive dust haze last week, particularly those living with respiratory illnesses.

Dust haze is a meteorological phenomenon in which dry dust or sand particles – largely originating in the Saharan Desert – are suspended in the air as they travel across the Atlantic from Africa to the Americas. Visibility is significantly reduced, typically to less than 10 kilometres, resulting in a milky, opaque, or slightly coloured sky.

Scientists have observed changes in the timing of dust events in recent years, according to Dr Andrea Sealy, the regional chair for the Americas for the World Meteorological Organisation’s Sand and Dust Storm Warning Advisory and Assessment System within the Caribbean Institute for Meteorology and Hydrology (CIMH).

“Coming into April and May… you’re getting a lot of dust, whereas before you might have gotten the dust later in May, maybe going into June…noticing a shift in terms of the severe dust episodes or, I should say, significant dust coming in, but also over the long-term period, dust transport has increased significantly,” she told Barbados Today on the Sidelines of medical education conference at Courtyard by Marriott on Sunday.

Satellite imagery continues to show large amounts of dust leaving the West African coast.

“So we are expecting more dust this time of year, and this is the time of year you would expect it. It kind of eased off during the week; it’s picking back up again because outside is hazy now. I expect that this might decrease, but you could get more dust in this time because this is the time of year you will expect, and it looks like it’s a pretty dusty period so far, because if you look outside, the last week or so was when we had the most of the dust.”  

Dr Sealy acknowledged that weather —  and climate-related advisories do not always reach the public effectively, although efforts are underway to improve communication.

“We’re in a position to put out that information. We have a basic knowledge, though, based on what the health community or the WHO would provide, so we know basic information, like because of their air quality guidelines, we know that over a certain amount of concentration of these particles would cause you to be outside running or you shouldn’t be outside for a long time because some people can’t help, but you gotta still go outside and do something, especially if you’re an athlete you’re training. We have a basic knowledge of that, but the health personnel will give more detailed information.”

Beyond forecasting dust events, CIMH is also expanding the region’s air-quality monitoring capabilities.

Dr Sealy revealed that the institute is working to strengthen air-quality monitoring across Barbados and the wider Caribbean, through the locally based University of Miami dust-monitoring station at Ragged Point.

“This year, between last year and this year, is about 60 years of dust measurements being done on the east side of the island, which makes it the longest dust observation. This is the oldest dust observation station globally, and it is right here in Barbados.”

The long-running record has made Barbados one of the most important locations globally for Saharan dust research.

The data collected over decades has also strengthened the region’s forecasting capabilities:

“Our model at CIMH was able to predict that dust episode and does a pretty decent job predicting others. It gives an idea of when dust episodes are expected to hit the island or hit the region, and the kinds of amounts we might expect, and we can do that about 5 days in advance.”

She explained that the enhanced monitoring network would focus heavily on tracking harmful particulate matter, commonly referred to as PM2.5 and PM10 – dust particles measuring from less than 2.5 to 10 microns in diameter, about 30 times smaller than the human hair.

With this information, CIMH hopes to expand its air-quality monitoring network throughout the Caribbean:

“We’re looking at installing combinations of which is the more expensive, more accurate type of sensors for reference method equipment for measuring air quality. In this case, for particulate matter for PM2.5 and PM10, but then there are lower-cost sensors, like what you call the PurpleAir sensors.”

The general public would be able to access data from brand PurpleAir-brand air sensors in real time, she said. While they may not be as accurate as reference-grade instruments, they can still capture important information, she added.

“They capture trends, you still have the low-cost sensors, and you get more of those. So we’re looking at making sure that in the Caribbean we can adequately respond to the need for measuring, monitoring and assessing air quality and predicting it as well.”

(LG)