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Saharan Dust

  • Plume of Red Saharan Dust Drifting Towards U.S. Gulf Coast

    Satellite images show that a vast plume of Saharan dust is drifting westwards over the Atlantic.

    And meteorologists are predicting that it will reach the U.S. by next week, if not sooner!

    Some of the dust could arrive in parts of the U.S. Gulf Coast, such as southern Texas, Louisiana and Florida, by next Wednesday

    This phenomenon is the result of tiny sand and mineral particles being swept up off the surface of the Sahara Desert by winds.

    A heavy concentration of Saharan dust is located over northwestern Africa and the eastern Atlantic Ocean. (WSFA)

    These particles are then carried by updrafts into an extremely dry and hot air mass known as the Saharan Air Layer, which forms above the desert between late spring and early fall.

    Strong winds frequently blow this dust-laden air layer — which extends between altitudes of 5,000 and 20,000 feet — westwards during this period of the year, transporting dust thousands of miles to the Caribbean, and U.S. Gulf Coast.

    Saharan dust could be over the Deep South by the middle and end of next week or before. (WSFA)

    Every year, hundreds of millions of tons of this dust can be blown across the Atlantic, with transport peaking between June and July.

    This video by NASA’s Scientific Visualization Studio / NASA Center for Climate Simulation shows the dust flying across the Atlantic Ocean:

    Health threat and risk

    Because of its very low concentrations and the tiny size of the particles, many people on the ground will probably not even notice the effects of the dust when it arrives next week, apart from perhaps the hazy skies and particularly intense sunrises/sunsets that it sometimes causes.

    Saharan dust can lead to vivid sunrises and sunsets. (WSFA)

    However, those with respiratory problems, such as asthma and allergies, as well as the elderly and young children, can be especially sensitive to the dust — which can be inhaled into the lungs — and may experience some irritation after prolonged exposure. You should limit your time outside if you are concerned about your health in these circumstances.

    Studies have associated exposure to tiny particles in the atmosphere with respiratory disorders such as asthma, as well as some cardiovascular disorders and other health problems. However, research looking at the health impacts of Saharan dust specifically is relatively limited, and the evidence is still inconsistent as to what role it may play in the development of disease in humans.

    Benefits of Sahara dust

    Despite the potential health risks, the dust may also provide some significant benefits. Scientists think that the dry, dusty Saharan Air Layer may help to suppress the development of hurricanes and more minor tropical storms.

    Saharan dust can cause a multitude of positive impacts in North and South America. (WSFA)

    Saharan dust changes the regional climate by reflecting and absorbing the sunlight, which decreases the sea surface temperature,” explains Bowen Pan from Texas A&M University’s Department of Atmospheric Sciences. “[This] decreases the energy supply to the storms. Additionally, dust also stabilizes the atmosphere.

    Some of the dust even reaches the Amazon region in South America where it helps to replenish nutrients in rainforest soils that are depleted by tropical rains

  • Saharan Dust Cloud Engulfs Caribbean, Hazardous Air Quality Warnings Issued for U.S.

    Massive Saharan dust cloud is engulfing the Caribbean as it heads toward the U.S., with air quality across much of the region falling to record hazardous levels. The phenomenon is described to be the most significant in 50 years, according to environmental health specialist Pablo Mendez Lazaro with the University of Puerto Rico.

    The vast cloud of dust, known as the Saharan Air Layer (SAL), has been dubbed "Godzilla dust cloud" by some experts, the Associated Press reported. 

    "Dust has been flowing off the coast of Africa for several weeks now, which is not uncommon," AccuWeather senior meteorologist and lead hurricane expert Dan Kottlowski explained.

    "But the extent and concentration of dust currently in the Caribbean are by far very impressive."

    "The depth of the dust, as measured in various places, suggests that this is one of the most concentrated areas of dust we have seen in the past several years," he added, although he acknowledged that dust concentration records are not well established.

    The dust reached Puerto Rico on Monday, June 22. The visibility at the airport on St. Croix, U.S. Virgin Islands dropped to 5 km (3 miles) and was limited to 8 km (5 miles) in San Juan, Puerto Rico.

    According to National Weather Service (NWS) meteorologist Gabriel Lorejo, the SAL plumes have allowed 16 km (10 miles) or more of visibility at the surface.

    "We have many models that indicate the highest dust concentration is from around 1 524 m (5 000 feet) all the way down to the surface. It’s pretty extreme," he said.

    Kottlowski noted, "this is probably the worst air quality caused by Saharan dust in recent memory."

    "Dust particles are like any other pollution such as smoke. Low-level dust is usually a very short-term issue such as when one experiences dust in a dust storm."

    He continued, "But this is different because it's not local dust, it's dust that originated at least 6 437 km (4 000 miles) away and has been falling out to the ground since then"

    Lazaro also pointed out that conditions are dangerous in many Caribbean islands. Many health specialists were concerned about patients battling respiratory symptoms to COVID-19.

    He added that the concentrations were so high in the previous days that it could have effects, even on healthy individuals. Limited visibility and extremely hazy conditions were reported from Antigua to Trinidad and Tobago. 

    "This is the most significant event in the past 50 years," Lazaro noted.

    As of Wednesday morning, air quality in Puerto Rico was fair, according to data from Plume Labs. However, SAL has blanketed some cars outside in a fine layer of dust.

    A small tropical wave headed toward the Caribbean is expected to ease the conditions by Thursday, June 26, according to Jose Alamo, a meteorologist with the NWS San Juan.

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