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 and CALPUFF) to evaluate the transport of air pollutants, such as fumigant emissions from buildings, criteria and toxic air pollutants from operating oil fields, and accidental release of chemicals from industrial facilities. 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.

Chan WR. National VOC emission standards for aerosol coatings. Metal Finishing 2009, November. http://www.metalfinishing.com/view/5019/national-voc-emission-standards-for-aerosol-coatings/.

Gunaseelan P, Buehler C, Chan WR. Greenhouse gas emissions: Characterization and management. Hydrocarbon Processing 2009, September; 57–70.

Bigham G, Chan W, Dekermenjian M, Reza A. Indoor concentrations of mercury vapor following various spill scenarios. Environ Forensics 2008; 9(2):187–196.

Chan WR, Nazaroff WW, Price PN, Gadgil AJ. Effectiveness of urban shelter-in-place. III: Commercial districts. Building Simul 2008; 1:144–157.

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

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

Chan W, Nazaroff W, Price P, Gadgil A. Effectiveness of urban shelter-in-place–I: Idealized conditions. Atmos Environ 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

Gunaseelan P, Buehler C, Chan WR. In profile: carbon dioxide emissions from U.S. petroleum refining. Air & Waste Management Association, Detroit, MI, June 16–19, 2009.

Chan W, Bigham G, Dekermenjian M. Exposure to elemental mercury from a spill. The 11th International Conference on Indoor Air Quality and Climate, Paper #127, Copenhagen, Denmark, August 17–22, 2008.

Chan W, Gauthier T, Murphy B. Calculation of Johnson and Ettinger model parameters using indoor air and soil gas measurements. The 11th International Conference on Indoor Air Quality and Climate, Paper #128, Copenhagen, Denmark, August 17–22, 2008.

Chan WR, Levy J, Murphy BL, Lingle J. Air emissions and exposure from remediation of former manufactured gas plant sites. Air & Waste Management Association 101st Annual Conference and Exhibition, Paper #341, Portland, OR, June 24–26, 2008.

Reiss R, Chan R. Estimation of emission rates for building fumigations. Methyl Bromide Alternative Outreach Conference, San Diego, CA, October 28–November 1, 2007.

Reiss R, Chan R. Impact of estimation methods and tarping methods on flux rates. Methyl Bromide Alternative Outreach Conference, San Diego, CA, October 28–November 1, 2007.

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
  

Modeled fugitive dust emissions to estimate the regional transport of herbicide via wind erosion. Work involved calculating the herbicide concentrations at the source and the soil particle size-dependent emissions for each wind events. Predictions were used to estimate the mass of herbicide transported and deposited on downwind fields.

Evaluated mercury vapor emissions for the different site remedial options proposed at a former chlor-alkali plant. The analysis back-calculated an emission rate based on the air monitoring data collected at a similar project site. This method allowed the use of best-available data to more reliably predict mercury vapor concentrations at a proposed remedial site.

Modeled criteria and toxic air pollutants concentrations at an operating oil field in Kuwait. Many sources were considered, including stack emissions, flares, and storage tanks. Predicted air pollutant concentrations were used to evaluate potential human health and environmental impacts. Predictions were compared with monitoring values to assess model performance.

Modeled accidental release of chemicals from an industrial facility. The air dispersion model CALPUFF was used because of the rapidly changing emission rates. Multiple chemicals were modeled. Predicted chemical concentrations were compared with air monitoring values that were taken as part of the emergency response effort shortly after the release.

Estimated pesticide drifts using the AgDRIFT model. Calculated the resulted range of pesticide concentrations in different water bodies, including streams and off-channel habitats. Model predictions were used to estimate the necessary buffer zone for spray applications to minimize risk to sensitivity species.

Applied TCE concentrations detected in outdoor air, indoor air, soil gas, and groundwater to parameterize the Johnson-Ettinger model. The parameterized model was used to quantify the contribution of soil vapor intrusion for a separate group of residences nearby. This method allows the use of site-specific data without relying on default assumptions alone.

Performed particle trajectory analysis to determine if fugitive emissions from bridge repair work could cause the alleged property damage. The analysis considered characteristics of the fugitive emissions (particle size and chemical composition) and local meteorology.

Critiqued an air monitoring study proposed by a regional air regulatory consortium. The proposed work involved using a novel air sampling instrument and a GIS-based technique to identify local hot-spots. Provided specific comments to the proposed statement of work regarding sampling technique and data analysis.

Designed an air sampling protocol to collect coal dust from rail cars during simulated wind tests. Installed and maintained real-time and filter-based aerosol instruments during the 3-month field work. Worked with a team of engineers to collect air samples and deposition measurements in order to characterize the dust reduction effectiveness of surfactants.

Reviewed emission inventory data and life cycle analysis to evaluate the greenhouse gas emissions from the transportation sector. Compared greenhouse gas emissions from petroleum refineries as a component of the fuel cycle emissions from oil extraction to end-use.

Evaluated proposed rulemaking by U.S. EPA on changes to lead national ambient air quality standards. Assessed implications to both the sampling and analysis method, and the air monitoring network design. Also commented on impacts to industrial emitters.

Analyzed odor measurements from an agricultural operation. Proposed methods to identify facilities that require emission control. Prioritize facilities according to the odor measurements and distance from sensitive receptors, such as the nearest residence and community buildings.

Characterize meteorological data to support various projects, such as evaluation of a particular weather event for structure damage cases and accidents. Also evaluated climatological data to assess long-term averages and to identify extreme weather events.

Estimated indoor concentration of volatile chemicals from industrial activities such as solvent use. Modeling considered building ventilation, source strength, and the exposure scenarios. Predictions were used to assess worker exposure in industrial hygiene evaluation.

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