Dust from Africa's Sahara traveled thousands of miles of the Atlantic Ocean to the U.S. and Caribbean, and this happens every year.
Researchers tested the air in the Houston area, and were able to determine which particles were home-grown and which were from somewhere else, a University of Miami press release reported. These tests allowed the team to profile a "fingerprint" of the far-off-desert dust.
The African dust could be harmful to people suffering from asthma and other breathing-related issues.
"Current EPA air quality standards are based on the total amount of particles that are in the air," Joseph Prospero, professor emeritus at the University of Miami Rosenstiel School of Marine and Atmospheric Science, said.
"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 respond to health and environmental issues linked to African dust," he said.
The study was the first that differentiated between native U.S. particles and African dust. The findings could be used to help other regions that receive an annual onslaught of the dust, such as the Caribbean. The dust can also effect extreme weather, such as hurricanes, in the area.
"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," Prospero said. "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 way, so that the relationship is not entirely clear. It is the subject of much ongoing research."
The dust can also block out sunlight, cooling the ocean in areas where hurricanes can form. Prospero said the dust activity has been strong this year, keeping the ocean's surface fairly cool. This could have been a contributing factor to the calm hurricane season.
The findings could help create models that would aid in predicting future weather patterns.
"The question is what happens with climate change," Prospero said. "Although much of North Africa is expected to get drier, which would mean more dust, models can't agree on whether the climate in the current major dust sources will get drier or wetter in the future."
