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Gall Research Group

Research Areas:

Materials and the indoor environment

A major focus of the Gall Research Group is investigating the role played by indoor surfaces in impacting indoor environmental quality. Materials are important in indoor environments – indoor surface area to volume ratios are about 300 times greater than outdoor environments. This means heterogeneous chemistry plays a key role in the fate and transformation of indoor pollutants. However, that factor of 300 only tells part of the story. That estimate comes from only a simple approximation of area – the projection of the extent of a surface. If we could consider internal areas of materials, that number would be many times larger. The presence of enormous surface area in indoor spaces opens up a wide variety of interesting chemistry and potential opportunities for passive removal of indoor pollutants.

One major thrust is improving characterization methods employed in the indoor air sciences by analyzing at the physicochemical properties of new and aged indoor surfaces, building envelopes, and air cleaning media. This includes characterizing surfaces for the presence of particular functional groups, porosities, pore size distributions, and macro-scale geometry. These investigations are paired with laboratory and modeling approaches to estimate what changes in pollutant-material interactions result from these changes in physical properties.  

Monitoring and modeling of human exposure to ambient air pollutants 

This work involves the development of personal monitoring approaches and application of a time-concentration-microenvironment models of human exposure to air pollutants. A major focus is the development of portable, personal monitors that enable real-time collection of pollutant concentrations, human behaviors, and well-being metrics. Outcomes include data and models describing i) the impact of behavior, building operation, and intra-urban variability in outdoor air pollution on exposure, ii) determination of best-estimates of time activity budgets for populations across age and gender subgroups in real-time, and iii) physical models and statistical methods that leverage the extensive data collected into actionable knowledge that improves building operation and human well-being. 

Indoor-outdoor air pollution relationships

Indoor and outdoor air quality are strongly connected. Buildings require ventilation air from outdoors to dilute air pollutants with indoor sources. Good outdoor air quality is therefore essential for buildings to achieve purpose. The GBRL is currently engaged in several projects that investigate the ways in which indoor and outdoor air are coupled.

Air quality impacts of ecoroofs

Along with colleagues from the PSU Honors College and Biology, the GBRL recently received funding to investigate the effects of ecoroofs (or green roofs) on indoor air quality.  In this work, research will focus on two fundamental questions: 1) How does the design of a building rooftop affect deposition, processing, and emissions of air pollutants? and 2) How might ecoroofs affect indoor air quality? This project will address these questions with a combination of extensive and innovative data collection that integrates ecology, biology, and building science approaches. Specific investigations will include a broad field survey of 48 roof surfaces in Portland, OR, an intensive air quality monitoring study at a commercial facility with a dual ecoroof/white membrane roof, and bench-scale laboratory investigations. Field measurements and laboratory parameterizations will be used in statistical models and material balances to explain relationships between the urban environment, ecoroofs, and indoor air quality.

Vertical distributions of outdoor air pollutants

In many urban environments, a substantial portion of population lives in mid- or high-rise construction, e.g., in Hong Kong around 40 percent of the population lives above the 14th floor. With a team of undergraduate researchers, we characterized the vertical distributions of air pollutants in three distinct locations in Singapore (another city characterized by substantial mid- and high-rise construction): the western coast where the Nanyang Technological University (NTU) is located which is characterized by lower building height, and fewer ground level sources of air pollutants and two sites in central Singapore with newer, higher elevation construction in close proximity to dense traffic. Forthcoming results will present the impact of spatial and temporal factors on vertical gradients of outdoor ozone and particulate matter. Implications for human exposure to air pollutants as a function of building height will be explored.