February 19, 2001

NC State Researchers’ Work Contributes to the Development of More Stringent Air Pollution Standards

Steady-state trace Gas Concentration Contours in a Human Inhalation Test Chamber

The orange-gray haze of smog that seasonally hangs over Raleigh is a relatively new and unwelcome arrival. A byproduct of the enormous growth in the Research Triangle area over the past 15 years, it is a harbinger of respiratory ailments to come – more incidents of asthma for children, more severe bronchitis cases for adults.

We can see evidence of the pollution all around us, especially during the summer months; but what can we really do about this problem? Dr. Clement Kleinstreuer, professor of mechanical and aerospace engineering at NC State University, and his collaborator Dr. Sinjae Hyun, research assistant professor of mechanical and aerospace engineering, are redesigning inhalation test chambers that can be used to provide high-quality information about the effects of toxic pollutants on humans. If we can learn more about the impact of various concentrations of airborne pollutants on human lungs, we may be able to determine and justify appropriate air quality standards proposed by the U.S. Environmental Protection Agency (EPA).

When testing subjects, researchers want to create conditions that will provide controlled data sets applicable to a real situation, not just to a laboratory setting. This is the challenge for Kleinstreuer and Hyun: design a chamber to predict the uptake of a given pollutant, such as carbon monoxide, ozone or particulate matter, in low concentrations on human volunteers in a real-world scenario. The trick is to provide a uniform air stream that will deliver the test pollutant to either a "couch potato" or a treadmill-walking subject in an even, predetermined concentration. Toxicologists and epidemiologists then correlate inhalation test chamber results, measured ambient pollutant levels and observed episodes of lung diseases.

Using computer simulations, the researchers address this fluid-particle dynamics problem by examining the air flow patterns around sitting or standing breathing mannequins strategically placed in a large test chamber and exposed to the controlled air flow. Transient three-dimensional flow simulations are used to determine subject inhalation and exhalation of the conditioned air flowing into the chamber. Accurate assessment of the amount of pollutant periodically inhaled by the subjects is a key task for the redesign of the air-pollutant delivery system. In a separate, micro-scale study, Kleinstreuer and coworkers predict the local surface concentrations of toxic particles in lung airway models under realistic breathing conditions.

These virtual reality simulations have sparked the interest of researchers and policymakers here and in Europe because, unlike many kinds of laboratory data, these numbers can be translated directly to the real-world environment. Kleinstreuer and Hyun hope their work will allow them to generate high-quality data in future dosimetry-and-health-effect studies with volunteers. In the battle to clean up our air, such data sets are essential.

-- rudd --

Technical Contact: Dr. Clement Kleinstreuer, 919-515-5261, ck@eos.ncsu.edu
Media Contact: Linda E. Rudd, 919-515-3848, linda_rudd@ncsu.edu

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