African Dust Storms Impact Air Quality in the U.S. and Caribbean

It goes to show that the weather on Earth really is connected. Scientists have discovered that massive dust clouds from the African Sahara can impact the air quality in both the U.S. and the Caribbean. Now, though, researchers have found a way to help measure and quantify the dust transported by these dust storms.

Each year, African dust storms affect the U.S. and the Caribbean. Particles are airborne and carried by air currents until they reach the North American continent.

"African dust storms are associated with hurricane season because the meteorological situations that are involved with generating tropical cyclones are also associated with the generation and transport of dust," said Joseph Prospero, one of the researchers, in a news release. "The dust emerges from the coast of Africa in a hot, dry, elevated layer-the Saharan Air Layer (SAL) following behind Easterly Waves from which tropical cyclones sometimes develop. The SAL interacts with the waves in complex ways, so that the relationship is not entirely clear. It is the subject of much ongoing research."

In order to learn a little bit more about how much these dust storms could affect air quality, the researchers examined particles in the air in the Houston region of Texas. There, they distinguished between particles transported across the Atlantic and those from local sources. In this way, they established the "fingerprint" of African dust.

"Current EPA air quality standards are based on the total amount of particles that are in the air," said Prospero in a news release. "Our study will contribute to our ability to discriminate and identify the dominant components in the air during long-range transport events. Our hope is that our work is instrumental in assisting regulatory agencies response to health and environmental issues linked to African dust."

Being able to measure how much dust reaches the U.S. could also help with future climate models. Dust suspended in the wind absorbs and scatters solar radiation. This causes less sunlight to reach the ocean surface and results in cooler temperatures in the tropical Atlantic Ocean.

"Dust activity has been very intense this year and sea surface temperatures are unusually low," said Prospero. "These may have been contributing factors to the unusually weak hurricane season this year."

The findings are important for better understanding the range and complexity of the Saharan dust storms. In addition, they could help assess the impact of African dust on climate and human health.

The findings are published in the journal Environmental Science & Technology.