Sahara Dust

Sahara Dust

1. The massive dust cloud arrived in Puerto Rico the Sunday before last, sweeping in and staining the evening sky a milky white. Monday and Tuesday, the air grew heavier with dust by the hour. Late on Tuesday, Olga Mayol-Bracero

   • This particular dust plume is at once remarkable and totally ordinary. Each year, these kinds of plumes sweep off the Sahara, carrying some 180 million tons of mineral-rich dust from its dried-out pans. Thousands of miles downwind, the fine-grained dust shapes both the ecology of the places it lands and the climate as a whole.
     • ¿EDust hurts health?
       • The dust in the Sahara plume is made up mostly of tiny bits of minerals that used to be rock. Typically, as a plume passes the Spanish Canary Islands, which sit a few hundred miles downwind of the desert sources
       • But themost of the dust that’s falling out is smaller than 20 microns in diameter, half as big as a particle that can be seen by the naked human eye. By the time a plume makes it across the ocean to the Caribbean

2. atmospheric chemist at the University of Puerto Rico, Rio Piedras, checked the readings at the atmospheric observation station she runs on the northeastern tip of the island. The numbers were higher than anything she’d seen in the 16 years she’s been taking measurements at the station.

   • But this year’s plume is remarkable because it appears to be the thickest and densest to cross the since the start of satellite monitoring, in 1979. Also, it’s carrying tons of lung-irritating fine particles toward North America, where chronic respiratory conditions are significant causes of disability and death.

3. The Saharan dust plume is a supersized version of ones that cross the Atlantic all the time, ferrying particles that irritate lungs but also fertilize plant and ocean life.

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