Wanyu Rengie Chan, Ph.D.

Dr. Chan has expertise in air quality modeling in both the outdoor and indoor environments. Her focus is on pollutant fate and transport between outdoor and indoor air, and human exposure to airborne pollutants.

Dr. Chan has used air dispersion modeling (e.g., AERMOD) to evaluate the transport of air pollutants, such as fumigants used to treat soil, and in buildings for commodity applications. She has conducted air sampling to determine pollutant concentrations in the ambient air using EPA-recommended methods. Dr. Chan’s studies of pollutant transport between outdoor and indoor air include a recent modeling assessment of dioxin mobilization from backyard burning and transport to attic surfaces. She has been involved in a number of projects to estimate human exposure to pollutants in residences and work places. Dr. Chan has modeled the effect of different emission scenarios, environmental conditions, and human activities on exposure. Because people spend most of their time indoors, Dr. Chan understands building ventilation and operation, and she has researched the air leakage characteristics of the U.S. building stock.

Prior to joining Exponent, Dr. Chan conducted research at the Airflow and Pollutant Transport Group, Lawrence Berkeley National Laboratory. There she collaborated with the National Atmospheric Release Advisory Center to develop an operational model that predicts indoor concentrations in homes and commercial buildings in the event of an outdoor chemical release. Her work has been applied in advising emergency responders on protecting buildings against accidental or intentional chemical or biological releases. Dr. Chan also participated in the Pittsburgh Atmospheric Particulate Matter Supersite Program led by Carnegie Mellon University. Her work involved ambient monitoring, instrumentation, and analysis of data on gaseous pollutants and particulate matter. She also assisted in the development of an in-situ instrument that measures the fine aerosol water content of ambient aerosol.

Bigham G, Chan W, Dekermenjian M, Reza A. Indoor concentrations of mercury vapor following various spill scenarios. Environmental Forensics; 2008, in press.

Chan WR, Nazaroff W, Price P, Gadgil A. Effectiveness of urban shelter-in-place–II: Residential districts. Atmospheric Environment 2007; 41:7082–7095.

Chan WR, Shields WJ. Deposition of dioxin in attics from backyard burning. Organohalogen Compounds 2007; 69:722–725.

Chan W, Nazaroff W, Price P, Gadgil A. Effectiveness of urban shelter-in-place–I: Idealized conditions. Atmospheric Environment 2007; 41:4962–4976.

Price P, Shehabi A, Chan W. Indoor-outdoor air exchange rates of California apartments and commercial buildings. California Energy Commission, CEC-500-2006-11, 2007.

Sherman M, Chan W. Building airtightness: Research and practice. In: Building Ventilation—The State of the Art. Santamouris M and Wouters P (eds), pp. 137–162, Earthscan, London, UK, 2006.

Chan W, Nazaroff W, Price P, Sohn M, Gadgil A. Analyzing a database of residential air leakage in the United States. Atmospheric Environment 2005; 39:3445–3455.

Stanier C, Khlystov A, Chan W, Mandiro M, Pandis S. A method for the in-situ measurement of fine aerosol water content of ambient aerosol: The dry-ambient aerosol size spectrometer (DAASS). Aerosol Science and Technology 2004; 38(S1):215–228.

Chan W, Price P, Gadgil A. Sheltering in buildings from large-scale outdoor releases. Ventilation Information Paper No. 10, Air Infiltration and Ventilation Centre, December, 2004.

Chan W, Price P, Gadgil A. NARAC Operational Integration Project Technical Report. Lawrence Berkeley National Laboratory. LBNL Report 56346, 2006.

Abstracts and Presentations

Chan W, Nazaroff W, Price P, Gadgil A. Factors affecting indoor health effects owning to an outdoor toxic release. 15th Annual International Society of Exposure Assessment Conference, Tucson, AZ, October 30–November 3, 2005.

Chan W, Price P, Gadgil A, Nazaroff W. Distribution of residential air leakage: Implications for health consequences for an outdoor toxic release. 10th International Conference on Indoor Air Quality and Climate, Beijing, China, September 4–9, 2005.

Chan W, Price P, Gadgil A, Nazaroff W, Loosmore G, Sugiyama G. Modeling shelter-in-place including sorption on indoor surfaces. 84th Annual Meeting of the American Meteorological Society, Seattle, WA, January 11–15, 2004.

• Lawrence Berkeley National Laboratory, Graduate Student Research Assistant, 2002–2006
• Pittsburgh Atmospheric Particulate Matter Supersite Program, Research Assistant, 2000–2001
  

Characterized exposure of downwind community from remediation of former manufactured gas plant sites. Performed indoor modeling to estimate concentrations in buildings where people might be exposed. Study demonstrates a methodology to evaluate the relationship between fence-line measurements and exposure concentrations under various excavation conditions.

Modeled downwind effects of air dispersion from methyl bromide building fumigation applications. EPA regulatory air dispersion models, AERMOD and ISC, were used to predict concentrations close to the building being fumigated. Determined an appropriate method for estimating buffer zones for fumigant applications.

Estimated fumigant flux rates following field applications. Analyzed concentrations measured directly above the field to estimate emission flux. Also performed air dispersion modeling to compute downwind concentrations. Compared model predictions with air monitoring data to back-calculate emission flux.

Modeled evaporation rate of mercury vapor to evaluate exposure concentrations. The model takes into account various environmental effects, including temperature, oxidation, and building air-exchange rate. Compared theoretical predictions with measurements from a room-scale test custom built in Exponent’s experimental facility in Phoenix.

Performed a modeling assessment of the fate and transport of PCDD/Fs from backyard burning to attic surfaces. This analysis demonstrates the mechanisms through which PCDD/Fs from a single backyard burn emission can deposit in an attic, and provides the basis for evaluating changes in congener profiles over time.

Conducted air sampling to determine PCB levels at the flightline of a major aircraft manufacturing and maintenance facility. The sampling was performed following regulatory method EPA TO-4A. Wipe samples were also collected from the flightline to determine PCB concentrations on concrete surfaces.

Evaluated past worker exposure to chemical solvents that contain TCE. Exposure reconstruction was based on building ventilation, emission rate, and application frequency. Predictions were compared with established exposure limits to determine whether exposure exceeded safety standards.

Investigated the effectiveness of shelter-in-place for a community in case of a large-scale airborne chemical release. Conducted various modeling case studies to identify the key parameters that influence sheltering effectiveness of residential and commercial buildings in urban areas.

• Air & Waste Management Association