Every year, about 800 million tons of dust is picked up by the wind from deserts in North Africa and blown across the Atlantic Ocean, traveling to the Amazon River Basin in South America, beaches in the Caribbean and, in part, into the air in North and South America.
"Hazy skies and low visibilities will continue today as a significant Saharan dust event continues across the islands", the National Weather Service in San Juan said Tuesday morning.
The Saharan dust to a hurricane is nothing more than extremely dry air.
NASA satellites measure the intensity of dust clouds with the Aerosol Optical Thickness (AOT) metric, which indicates the degree to which aerosols prevent the transmission of light through the atmosphere.
The particles can also make their way to ground level, potentially affecting those with dust allergies.