SAN JUAN, Puerto Rico -- A massive plume of Saharan dust has shrouded swathes of the Caribbean, turning blue skies into a milky-brown haze and sparking health warnings across the region as air quality fell to unhealthy levels.
Strong warm winds over the Sahara desert typically whip up sand at this time of year and carry it thousands of miles across the Atlantic Ocean to the United States.
This year, the dust is the most dense in a half a century, according to several meteorologists.
The thick smog has sharply reduced visibility.
The dust cloud moved into the eastern Caribbean during the weekend, and by Tuesday had smothered Hispaniola, Jamaica, Puerto Rico and eastern Cuba, continuing its advance up and westward toward Central America and southern United States.
Officials across the region warned locals to remain at home when possible and wear a face mask, especially if they already had a respiratory condition, as the dust was a powerful irritant and could contain pathogens as well as minerals.
Saharan dust cloud blankets Caribbean before heading to US