Indian-American scientist on trail of polluters

January 13th, 2009 - 2:37 pm ICT by IANS  

Washington, Jan 13 (IANS) Cloaked in the clouds of emissions and exhaust that hang over the city are clues about the polluting culprits.A University of Houston (UH) research team, headed by Shankar Chellam, is hot on their trail. The case hinges on unique identifiers found in fine particulate matter, a mixture of organic, inorganic or metal material.

This material is given off by natural sources, such as sea spray and grassfires, and manmade sources, such as vehicles and industrial operations, and then suspended in the air.

“Fine particulate matter is tiny - about 30 times smaller… than a human hair - but it carries in it a lot of information about where it came from,” explained Chellam, environmental engineering professor at UH’s Cullen College of Engineering.

Like any good detective, Chellam has enlisted a team with varying expertise, including urban air quality expert Matthew Fraser of Arizona State University, UH doctoral students of engineering and a NASA scientist.

Chellam, who did his B.Sc and M.Sc in mechanical engineering and chemistry respectively from the Birla Institute of Technology and Science, Pilani, India, and Ph.D in environmental science and engineering from Rice University, Houston, said scientists are only beginning to understand the biochemical basis of how airborne fine and coarse particulate matter and its individual components affect human health.

When their investigation started six years ago, Chellam said: The team was surprised, “maybe naively,” that most research at the time focused on ozone, which is formed when emissions mix with sunlight. Much less attention was paid to airborne particulate matter in the Houston area.

“Most previous studies have been concerned with gases, particularly ozone,” Chellam explained.

“It is the particulate matter - both fine matter that is smaller than 2.5 micrometers and coarse matter that is larger than 2.5 micrometers, but smaller than 10 micrometers - that we are interested in.”

Chellam said identifying pollution sources - even if only by industry or machine type, rather than individual factory or operator - is a public safety issue, because fine particulate matter is easily absorbed by the lungs and enters the bloodstream, said a UH release.

“Studies show that people living close to highways and refineries are more likely to become seriously ill,” said Chellam.

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