Research

Theme 1

Deposition vs. oxidation

Modeling the impact of deposition of gaseous organic compounds on atmospheric oxidation.

• Developed a framework of competition between oxidation and deposition and demonstrated that reactive organic carbon in the transition regimes accounts for a major fraction of both atmospheric reactivity and potential for secondary aerosol formation.
• Demonstrated an approach to estimate the timescales of wet deposition of gaseous organics using basic real-world precipitation data.
• Investigated the impact of deposition on atmospheric chemistry using a 0-d box model of photochemical oxidation and regional air quality models.

Theme 2

Instrumentation development

Isomer-resolved measurements of particle-phase organic compounds.

• Developed a field-deployable, online instrument for isomer-resolved quantification of particle-phase organics by coupling a flame ionization detector (FID) and a chemical ionization mass spectrometer (CIMS) to a gas chromatograph (GC).
• Demonstrated using a coupled FID as a calibration tool for quantifying CIMS sensitivity to unknown species, and applied it to examine the “voltage-scanning” method.
• Quantified the bias in log-linear calibration curves and developed a parameter-explicit solution that removes it.
• Studied the isomer-resolved composition of SOA in an oxidation flow reactor, and SVOCs in a university conference room during a two-week deployment.

Novel instruments for PFAS measurements.

• Evaluated superoxide chemical ionization mass spectrometry (O₂⁻ CIMS) for real-time, gas-phase measurements of per- and polyfluoroalkyl substances (PFAS).

Theme 3

Indoor air quality and exposure

Wildfire smoke and indoor surfaces.

• Measured how interior paint changes the re-emission of reactive organic carbon (ROC) from drywall contaminated by wildfire smoke.

Emission, fate, and transport of phthalate plasticizers in a residential test house.

• Investigated the partition dynamics by monitoring phthalate concentrations in air and on various indoor surfaces (e.g., dust, clothing, windows, mirrors, dishware) in a full-size residential test house with controlled indoor temperature over a year.
• Developed and validated a room-scale SVOC emission and transport model using the measured data in the test house.

Direct transfer of SVOCs from indoor source products to dust.

• Monitored the accumulation of phthalates and phthalate alternatives in dust settled on vinyl floorings and crib mattresses in a custom test chamber.
• Developed a mechanistic model to predict the elevated phthalate concentrations in dust in contact with the source materials.
• Estimated children’s potential ingestion exposure to dust-phase SVOCs through frequent dust pick-up and hand-to-mouth behaviors.

SVOCs in the dust of U.S. low-income homes and childhood asthma.

• Organized field operations and measured phthalates and organophosphates in settled floor dust and HVAC filter dust in winter and summer in 59 low-income homes in Texas.
• Investigated associations between SVOC concentrations and building characteristics with statistical methods.
• Found a positive association between childhood asthma severity and SVOC levels in HVAC filter dust.

Theme 4

System of systems

Integrated assessment across building and urban scales.

• Reviewed, categorized, compared, and evaluated existing assessment approaches to socio-environmental problems at the building and city scale.
• Proposed a unified framework based on the system-of-systems concept that connects the building and urban environment.