Saharan Dust Is Plaguing the Southern U.S.—But It May Prevent Deadly Storms

This image taken in 2009 shows Saharan dust blowing off the coasts of Mauritania and Senegal. NASA Earth Observatory

Dust from the Sahara Desert has been plaguing Texas and much of the southern U.S. in recent weeks, contributing to hazy skies and spectacular sunsets.

While this dust can be an irritant, it may also prevent potentially deadly storms from forming, according to a study published in the Journal of Climate.

Researchers from Texas A&M University analyzed recent NASA satellite images and computer models to understand more about the dust, which has been blown westward over the Atlantic by strong air currents, traveling more than 5,000 miles before reaching North America.

According to the scientists, the dust can affect temperatures in a way that prevents the formation of clouds. This means that when dust is present, both minor storms and more powerful hurricanes are less likely to develop.

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

For the latest dust intrusion, the team found that cloud formation in the area studied was suppressed.

"We saw few cumulus clouds over the last few days," Renyi Zhang, also from Texas A&M's atmospheric science department, said in a statement. "Dust particles reduce the radiation at the ground but heats up in the atmosphere, both leading to more stable atmosphere. Such conditions are unfavorable for cloud formation."

The most recent satellite images clearly show Saharan dust moving into much of the Gulf of Mexico and southern Texas, according to the researchers. This phenomenon is not unusual, occurring multiple times a year, usually between late spring and early fall.

Once released from the desert surface, these dust particles are carried by updrafts into the Saharan Air Layer—an extremely hot and dry layer of the atmosphere that sits above the desert itself and overlies a layer of denser marine air above the Atlantic. The dust is then blown westward by air currents located between 5,000 and 20,000 feet above the surface.

Airborne dust can present risks to human health, particularly for those with lung conditions such as asthma, older people or allergy sufferers.

"Particles larger than 10 μm are not breathable, thus can only damage external organs—mostly causing skin and eye irritations, conjunctivitis and enhanced susceptibility to ocular infection," according to the World Meteorological Organization (WMO).

"Inhalable particles, those smaller than 10 μm, often get trapped in the nose, mouth and upper respiratory tract, thus can be associated with respiratory disorders such as asthma, tracheitis, pneumonia, allergic rhinitis and silicosis. However, finer particles may penetrate the lower respiratory tract and enter the bloodstream, where they can affect all internal organs and be responsible for cardiovascular disorders," the WMO said.

The dust can also have negative impacts on agriculture, including reducing crop yields by burying seedlings, causing loss of plant tissue, reducing photosynthetic activity and increasing soil erosion. However, in some cases it may also act as a natural fertilizer and is an important provider of nutrients to both the Amazon rainforest and coral reefs, Pan said.

This article has been updated to include additional comments from Bowen Pan.