Assessing and controlling concentrations of volatile organic compounds in the retail environment

Nirlo, Éléna Laure
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Retail buildings have potential for both short-term (customer) and long-term (occupational) exposure to indoor pollutants. A multitude of sources of volatile organic compounds (VOCs) are common to the retail environment. Volatile organic compounds can be odorous, irritating or carcinogenic. Through a field investigation and modeling study, this dissertation investigates exposure to, and control of, VOCs in retail buildings. Fourteen U.S. retail stores were tested one to four times each over a period of a year, for a total of twenty-four test visits. Over a hundred parameters were investigated to characterize each of the buildings, including ventilation system parameters, and airborne pollutants both indoors and outdoors. Concentrations of VOCs were simultaneously measured using five different methods: Summa canisters, sorbent tubes, 2,4-dinitrophenylhydrazine (DNPH) tubes, a photoionization detector (PID), and a colorimetric real-time formaldehyde monitor (FMM). The resulting dataset was analyzed to evaluate underlying trends in the concentrations and speciation of VOCs, identify influencing factors, and determine contaminants of concern. A parametric framework based on a time-averaged mass balance was then developed to compare strategies to reduce formaldehyde concentrations in retail stores. Mitigation of exposure to formaldehyde through air cleaning (filtration), emission control (humidity control), and targeted dilution (local ventilation) were assessed. Results of the field study suggested that formaldehyde was the most important contaminant of concern in the retail stores investigated, as all 14 stores exceeded the most conservative health guideline for formaldehyde (OEHHA TWA REL = 7.3 ppb) during at least one sampling event. Formaldehyde monitors were strongly correlated with DNPH tube results. The FMM showed promising characteristics, supporting further consideration as real-time indicators to control ventilation and/or environmental parameters. The vast majority of the remaining VOCs were present at low concentrations, but episodic activities such as cooking and cleaning led to relatively high indoor concentrations for ethanol, acetaldehyde, and terpenoids. Results of the modeling effort demonstrated that local ventilation caused the most uniform improvements to indoor formaldehyde concentrations across building characteristics, but humidity control appeared to have a very limited impact. Filtration used under specific conditions could lead to larger decreases in formaldehyde concentrations than all other strategies investigated, and was the least energy-intensive.