This grant funds work by Paul Ziemann, professor of chemistry at the University of Colorado, to investigate the sources and processes that influence the composition of organic chemicals in indoor environments and to improve predictions of the chemistry of indoor air. Ziemann and his team will conduct field studies in several locations on and around the University of Colorado campus. Study sites have been chosen to reflect the diversity of indoor environments: a carpeted meeting room in the Sustainability, Energy, and Environment Community building; the Chapel Theatre in Old Main, which is the oldest building on campus and which contains extensive wooden paneling; and the swimming pool at the universityХs recreation center. State-of-the-art instruments and methods will be used to measure organic chemicals and other reactive species at each site. Measurements will include gas (volatile organic compounds and other trace gases), aerosols, surface composition (functional groups and single compounds), and air exchange. Laboratory studies will be conducted to investigate the fundamental interactions of organic chemicals with surfaces composed of common indoor materials, including bare plastics, bare wood, varnished wood, and carpet polymers. Results of the field and laboratory studies will be used to develop models to describe and quantify indoor chemical emissions, deposition, and reactions; and to determine the effects of chemical and physical variables such as organic gases, oxidants, surfaces, humidity, acids, light and temperature, and human occupancy on the composition of indoor air.

Funds from this grant support an ongoing project led by Marina Vance, assistant professor of mechanical and environmental engineering at the University of Colorado, Boulder, and Delphine Farmer, associate professor of chemistry at Colorado State University, to build community and data infrastructure for researchers working in indoor chemistry. Over the course of the grant period, Vance and Farmer will develop a data sharing infrastructure for indoor chemistry studies, merge and synthesize data collected from the HOMEChem field experiment with additional chemical datasets, further analyze that data, plan and host a scientific meeting for researchers in the Chemistry of Indoor Environment program, and continue outreach and community building among indoor chemistry researchers through the IndoorChem website and social media properties.

This grant funds research by surface chemist Franz Geiger, Dow Professor of Chemistry at Northwestern University, that will investigate the fundamental chemistry of indoor surfaces. Using advanced spectroscopy, Geiger plans to expand our understanding of how indoor volatile and semivolatile organic compounds absorb from air to surfaces; how submonolayer amounts of these absorbed organic compounds convert into indoor molecular, nano-, and microlayers; the propensity of these newly formed layers to interact with oxidants; and how the dynamic response of molecular, nano-, and microlayers to gas-phase species vary with changes in relative humidity. The approach includes both mechanistic studies of idealized model surfaces as well as work on surfaces of samples derived from real-world indoor environments. Results will be shared through peer-reviewed publications and presentations at conferences and meetings.

The Modeling Consortium for the Chemistry of Indoor Environments (MOCCIE) is a multi-institutional collaboration devoted to developing comprehensive, integrated, physical-chemical models that simulate how occupants, indoor activities, and buildings influence indoor chemical processes. Founded with Sloan support in 2017, and overseen by Manabu Shiraiwa, Associate Professor of Chemistry at the University of California, Irvine, and Nicola Carslaw, Reader, University of York, MOCCIE links and modifies existing chemical models across a diverse range of physical scales and timeframes. The consortium also partners with experimental chemists working on the indoor environment in mutually beneficial ways. Experimental data can be used to test MOCCIE simulations, resulting in better predictions. These improved predictions, in turn, can then be used by experimentalists to generate hypotheses for further testing. Funds from this grant provide 18 months of continued support for MOCCIE. Over that time, MOCCIE will assess gaps in the fundamental understanding of indoor chemistry processes, guide experimental measurements through identification of parameters responsible for model uncertainties, indicate key species with predicted concentrations, improve design of experimental/fieldwork studies, and aid in interpretation of data from laboratory and field experiments.

This grant funds research by Michael S. Waring, Associate Professor of Architectural and Environmental Engineering and Peter DeCarlo, Associate Professor of Environmental Engineering and Chemistry at Drexel University, that will examine the chemical and physical transformations occurring within a heating, ventilation, and air conditioning (HVAC) system. Waring and DeCarlo’s work will focus on aerosol and gas-phase transformations, exploring how aerosol processing, composition, and component-based filtration are influenced by extreme and abrupt changes in temperature, relative humidity, and aerosol concentration as air is thermally conditioned and filtered. Utilizing a controllable HVAC system in a Drexel office building, Waring and DeCarlo will make seasonal measurements of the chemical composition of aerosols and trace gases at four locations in the HVAC system—outdoor, mixed, supply, and return air—to isolate the impact of HVAC system aerosol and gas composition. Aerosol composition will be measured using a high-resolution aerosol mass spectrometer with other instruments capturing trace concentrations of CO, CO2, H2O, O3, NO, NO2. Grant funds also support Waring and DeCarlo’s continued analysis of data collected during 2018’s Sloan-funded HOMEChem field project.

This grant supports a collaboration between Paul Wennberg, R. Stanton Avery Professor of Atmospheric Chemistry and Environmental Science and Engineering, California Institute of Technology, and Henrik Kjaergaard, Professor of Chemistry at the University of Copenhagen, to examine the role of autoxidation (a series of unimolecular processes that rapidly yield oxidized compounds) in indoor environments. Kjaergaard will use computational chemistry methods to diagnose the autoxidation pathways and estimate the rate coefficients for the organic peroxy radical chemistry initiated by the reactions of ozone and the hydroxyl radical with chemicals typically found indoors, especially a suite of terpenes. Complementing this approach, Wennberg will study terpene chemistry in the laboratory to evaluate the computational work and provide guidance for how to extend the calculations to more organic substrates. The pair will publish a suite of mechanistic schemes that describe the chemistry in peer-reviewed manuscripts, present their findings at conferences and meetings, and integrate their work into existing indoor chemical models.