UH Professor to Study Air Pollution in Underwater Tunnel

An underwater traffic tunnel may seem an unlikely place to study air quality, but a University of Houston professor believes the Washburn Tunnel will provide the ideal setting to analyze vehicle emissions.

Shankar Chellam, a professor of civil and environmental engineering at UH, is researching the unique chemical makeup, or "fingerprints," of various sources of air pollution.

Much of Chellam's previous research has examined industrial sources of pollution such as petroleum refineries, but he recently received a $75,600 grant from the Texas Air Research Center to find the pollution fingerprint of gasoline-driven vehicles.

Chellam noted that it's much more challenging to identify the pollution caused by vehicles than by stationary industrial sources. A sensor placed at an industrial site can provide an essentially undiluted sample of that site's emissions. But vehicles operate out in the open air, where their exhaust mixes with pollution from other sources, making it difficult to get an exact measurement, Chellam said.

Enter the Houston area's Washburn Tunnel - the state's only operational underwater vehicle tunnel. The two-lane tunnel runs underneath the Houston Ship Channel, connecting the Houston suburbs of Galena Park and Pasadena. It's closed to diesel-powered semi-trucks.

 "If we sample the air in this tunnel, the chances of other sources impacting our sample are very, very slim," Chellam said. "Whatever we measure can be directly attributed to the vehicles that go through the tunnel."

Working with post-doctoral researcher Suresh Kannan and doctoral student Nick Spada, Chellam first will design the methods for measuring metals emitted by automobiles, a process that will take about a year.

Air samplers then will be placed in the tunnel to measure particulate matter emissions. By measuring pollution produced by thousands of cars over hours and even days at a time, Chellam and his team will be able to determine the real-world make-up of the airborne particulate matter pollution arising from gasoline-driven vehicles.

While the immediate goal of this research is simply to identify the chemical fingerprint of automobile exhaust, Chellam hopes that his work ultimately will be used to make life in cities, and elsewhere, more livable. As large metropolitan areas struggle to adhere to government-mandated standards regarding air pollution, they need to know exactly what chemicals are in different pollution sources.

"What we hope is that by communicating our findings, there may be some environmental policy decisions made based on our research and similar work that others are doing," he said.