The industry-lined Houston Ship Channel is one of the world’s largest concentrations of oil refineries, petrochemical plants and associated industrial facilities and transportation systems.
As a result, nearby residential neighborhoods have been the focus of decades of concerns and controversy surrounding industrial emissions of a broad group of health-threatening chemical compounds called air toxics.
Benzene, for instance, which is commonly associated with many oil and petrochemical operations, presents worries because of both its potential short-term and long-term effects. In the short-term, according to the U.S. Environmental Protection Agency, exposure to benzene can cause symptoms such as dizziness, headaches and respiratory irritation. Long-term exposure has been definitively linked to maladies including cancer.
With so many potential sources of benzene and other air toxics along the Ship Channel, it has long been a major challenge for regulators and researchers to say precisely where measured levels of these chemicals are coming from. A related question is likewise fraught with complexity: What health effects, if any, are residents near industrial facilities experiencing because of their exposure?
This fall, HARC will lead a multi-institution research campaign in three Ship Channel communities with long histories of air pollution issues – Manchester, Milby Park and Galena Park – to shed new light on those questions. The ultimate goal is to help improve air quality and public health in those and other near-industry neighborhoods.
The federally-funded BEE-TEX Study (the name is an acronym for “Benzene and other Toxics Exposure”) has been planned and is being overseen by Eduardo (Jay) Olaguer, HARC’s Program Director for Air Quality Science.
Olaguer believes the study, several years in preparation and employing an innovative combination of techniques for monitoring air pollutants, can help reduce emissions of those chemicals – both along the Ship Channel and in other similar locations elsewhere.
“I think the work that we’re doing will provide the kinds of methods that will clarify where these things are coming from,” he said, “so we can do something about it.”
The research project will include several key elements.
Computer-aided tomography, or CAT – essentially the same technology used for doctors’ diagnostic CAT scans of internal body structures – will portray the total concentrations of toxic pollutants as they travel along long pathways through the air.
These scans will use remote-sensing readings from a technology called Differential Optical Absorption Spectroscopy, or DOAS, which measures pollutants’ concentrations on the basis of their specific light-absorbing characteristics. Specialists at the University of California-Los Angeles have been building and will operate this network of monitors, which will be deployed in Manchester.
Complementing the CAT-DOAS effort will be at least two mobile pollution-monitoring labs that will measure pollutants and broadcast the resulting real-time data instantly to participating investigators. That way, those experts can, if warranted, hasten to perform what Olaguer calls “adaptive measurements” of their own.
“If a van is picking up high measurements, everyone will know and we can say it seems like there’s an emission event and hurry more (monitoring) resources in that area,” he explained.
HARC will operate one of the mobile monitoring labs in Manchester, while Aerodyne Research, Inc., a Massachusetts-based company with pollution-monitoring experience in the Ship Channel area, will operate a lab that roams among the three communities under study.
With the mobile labs, researchers can quickly travel to a specific location with high pollutant levels and then remain in the chemical cloud, taking continuous measurements as this plume of pollutants as it travels away from its source and across a larger area, Olaguer said.
This approach offers a new way to measure pollutant levels and locations over space and time in a neighborhood with industrial facilities nearby, he said. Traditionally, regulators and researchers, relying on stationary monitors that only take a limited number of pollution samples, have had to be very lucky to obtain a broader, overall picture of the air quality across an entire near-industry community, he added.
Another innovative feature of the BEE-TEX project will involve researchers from the University of North Carolina operating a new instrument that will expose cultured human lung cells to polluted air.
These experts will be measuring proteins and enzymes that the cells release to determine if they’re are stressed or even dying in reaction to the effects of chemical pollutants. Cells’ responses may indicate exposure to specific classes of air pollutants. Genetic studies, meanwhile, will be conducted to determine if cells are demonstrating a response to toxic compounds that signal carcinogenic changes.
BEE-TEX will mark the first time this kind of cell-exposure testing is conducted in the field, in real-world settings near pollution sources, Olaguer said.
Another major tool that will be employed in the research effort will be the HARC Air Quality Model, a neighborhood-scale computer model developed by Olaguer in recent years.
This model can infer the movement of emissions from concentrations of pollutants recorded in the air, as well as predict their future concentrations and wind-borne trajectories. It will be used for determining the sources of measured pollutants and mapping their plumes based on CAT scans.
Olaguer believes this varied combination of methods and technologies that have been assembled for the BEE-TEX project will offer a promising new approach for researchers and regulators not just in the Houston area but elsewhere, as well.
At present, there are two major approaches to the measurement and assessment of air pollutants, he said. One, which has been used for decades, involves monitoring stations that are both expensive themselves and costly to operate. Another involves equipping non-expert citizens with mobile monitors that are less expensive but sometimes produce findings shadowed by questions about the quality and reliability of the collected data.
The BEE-TEX approach that will be tested in HARC’s upcoming study represents a promising “third way,” Olaguer said – one that also requires expensive equipment, as traditional government monitoring efforts do, but equipment that can readily be moved around to cover a much larger area and produce a much more complete picture of air pollution in an area.