This is an amazing natural phenomenon that has been going on since the Sahara Desert was formed between 4000 to 5000 years ago. But as with most scientific data on Mother Nature's events, scientists cannot agree:
"Mojena said the dust arriving in Cuba has risen 10-fold in the last 30 years after severe droughts in northern Africa, though Omar Torres, a specialist in atmospheric physics at the NASA Goddard Space Flight Center in Maryland, said satellite studies since 1980 do not show increased Sahara dust emissions beyond normal seasonal variability."
We live on such a wondrous planet!