Shankar Chellam, who has been teaching at UH since 2004, has been researching Saharan dust. | Courtesy Photo/ The Daily Cougar
Civil and environmental engineering professor Shankar Chellam has been studying African dust in comparison to the pollutants in our air that are “homegrown.”
The research idea came about while Chellam was working on another project in 2008, collecting data on the industrial air outside plants in the Houston Ship Channel. At the time, he predicted that the pollution amount emitted would be constant, but he noticed the emission levels were higher on some days.
Chellam found that the spike in the pollution levels was due to the arrival of Saharan dust.
Working with professor Joe Prospero of the University of Miami, the two first looked at satellite images of the dust as it made its way to Houston from North Africa. Following this, they analyzed elements of the dust collected in Barbados before the dust had reached Houston and compared it to ambient dust collected in the Ship Channel area.
“We found very strong similarities in elemental composition of our local dust and Barbados, which is excellent evidence that North African dust was responsible for increases in our local pollution,” Chellam said. “We also performed computer modeling to quantify the impact of various local and global sources, which pointed to a very strong contribution of mineral dust from the Sahara desert. My collaborator (Prospero) also looked at meteorological evidence for long-range dust transport.”
Often during hurricane season, the North African dust gets picked up by wind and pushed westward into the Atlantic Ocean, according to AccuWeather. The dust enters Houston three to five times each summer, and aside from a haze, this may be to blame for higher allergies in the area during those periods.
“Saharan dust is mineral dust, which has a different chemical composition than dust emanating from our local industries,” Chellam said. “I am not a toxicologist, but I expect that there will be differences in the health risks based on the metal content of the dust. If the aerosol concentration is sufficiently high, it would be best for people with respiratory illnesses to not be exposed to ambient airborne particulate matter. There is also general information available that being exposed to high concentrations of any kind of dust over prolonged periods induces premature death.”
A paper on Chellam and his team’s findings has been accepted for publication in “Environmental Science and Technology,” but he’s not finished yet. He plans on continuing his research through analyzing other episodes to see similarities in chemical composition between dust collected in Houston and Barbados.
