Dr. John C. Little
Characterizing sources of volatile compounds in the indoor environment
Building materials are one of the primary indoor sources of volatile compounds,
contributing to poor indoor air quality. We are developing fundamental models
that predict emissions from several generic types of building material, and testing
rapid procedures to measure model parameters. Our methods include formulation of
mechanistic models, development of solutions using analytical techniques, dynamic
microbalance experiments for rapid determine of diffusion and partition coefficients,
and limited large-scale chamber tests to provide data for model validation.
Fluidized bed desorption unit
developed to extract volatile contaminants from
cryogenically-milled building materials.
Exposure to chemical contaminants in drinking water
To establish drinking water standards, potential exposure to the entire range of contaminants
must be evaluated. A series of mathematical models is being assembled in a software package
that evaluates human exposure to all chemical contaminants found in drinking water, based on
their chemical properties. The model predicts exposure via ingestion, inhalation, and dermal
sorption. A Monte Carlo analysis is employed to estimate the uncertainties associated with the
exposure predictions. The program includes an easy to use visually-based user-interface.
Dr. Linsey C. Marr
Particle laboratory and field experiments
Particles in the atmosphere play critical roles in public health, global climate change,
visibility, and atmospheric chemistry, and we are interested in better quantifying their
emissions and chemical transformations. Current projects include the characterization of
ambient particles in Mexico City by measuring their chemical and surface properties.
Specifically, we are investigating particulate polycyclic aromatic hydrocarbon (PAH)
concentrations and how they vary with aerosol surface area depending on the source of
the particles, their age, and meteorological conditions. We are also building a constant
soot source to be used for instrument calibration and laboratory experiments.
Urban and regional scale air quality modeling
One-third of the country’s population lives in areas with unhealthy ambient ozone levels,
and control strategies aimed at reducing precursor emissions of volatile organic compounds
and nitrogen oxides have not always succeeded. Photochemical air quality models can be used
to test the effects of projected emissions reductions. Recent research has focused on the
influence of gaseous motor vehicle emissions on ozone formation, in particular, why ambient
ozone tends to be higher on weekends than on weekdays in many urban areas. Investigation of
this phenomenon using a three-dimensional photochemical model has shown that higher weekend
ozone is due mainly to the decrease in emissions associated with reduced diesel truck
traffic on weekends. Models can be used not only as a policymaking tool but also to improve
the understanding of the emissions, chemistry, and meteorology used to drive them.
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2003
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