<b>How human activities and ventilation systems impact indoor air composition and chemistry in buildings</b>
Creators: name: Jiang, Jinglin
Publisher: name: Purdue University Graduate School
Year: 2024
Subjects: classificationCode: 400501
subject: Architectural engineering
classificationCode: 401199
subject: Environmental engineering not elsewhere classified

description: As people in the U.S. spend 90% of their time indoors, their exposure to indoor air pollutants released during the use of household consumer products cannot be overlooked. Studies have shown that consumer products such as disinfectants, cleaning agents, and personal care products (PCPs) contain complex mixtures of volatile organic compounds (VOCs). Monoterpenes, added as active ingredients in cleaning agents and fragrances, are commonly detected in these products. Monoterpenes can react with ozone (O<sub>3</sub>) and initiate the formation of secondary organic aerosol (SOA). Siloxanes, another category of compounds commonly found in PCPs, can bioaccumulate and may adversely impact the environment and human health.<br>Most prior studies have evaluated chemical emissions from these products using offline techniques, such as sorbent tube sampling followed by gas chromatography-mass spectrometry (GC-MS). Few studies have been conducted during real-life use of these products in indoor environments. Considering that many indoor activities are often transient, the composition of indoor air can be rapidly altered. Real-time monitoring of indoor VOCs and aerosols is necessary to capture the temporal variations in emissions during indoor activities and to evaluate their impact on indoor air chemistry, human exposure, and outdoor air quality. In addition, O<sub>3 </sub>also plays an important role in indoor chemistry. Indoor O<sub>3 </sub>concentrations are strongly linked to ventilation system operation and occupancy patterns, as the ventilation from outdoors is the major source of indoor O<sub>3</sub> and occupants are a major sink of indoor O<sub>3</sub>. However, studies on how ventilation modes and occupancy impact spatiotemporal distributions of indoor O<sub>3 </sub>are limited.<br>Hazardous chemical incidents can potentially be another unexpected source of indoor pollutants, releasing volatile chemicals which can be transported to indoor environments via building ventilation. Evaluation of air, water, and soil contamination and human exposure risks is critical in the emergency response to hazardous chemical incidents, to develop effective remediation strategies. An effective and reliable approach to assess air, water, and soil contamination, and subsequent human exposures, is urgently needed.To fill these research gaps, this dissertation aims to: (1.) characterize gas- and particle-phase emissions in real-time during common indoor activities, including surface disinfection, cleaning, and hair styling; (2.) evaluate the impact of indoor emissions on human health and the atmospheric environment; (3.) map the spatiotemporal distribution of O<sub>3</sub> and CO<sub>2</sub> concentrations throughout a building ventilation system; (4.) develop a methodology for rapid screening of VOCs in surface water samples collected from a chemical disaster site.<br>To achieve research goals (1.) and (2.), a field campaign was conducted at the Indiana University Research and Teaching Preserve (IURTP) field laboratory in summer 2019 and two field campaigns were conducted at the Purdue zero Energy Design Guidance for Engineers (zEDGE) Tiny House in fall 2020 and summer 2021 to characterize emissions from the use of cleaning agents, disinfectants, and hair care products in indoor environments, respectively. A proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) was used to monitor the mixing ratios of VOCs in real-time. To achieve research goal (3.), a multi-point sampling system was created at the Herrick Living Laboratories and its ventilation system in spring and summer 2019 to monitor spatiotemporal trends in O<sub>3 </sub>concentrations. To achieve goal (4.), a controlled static headspace sampling system, in conjunction with a high-resolution PTR-TOF-MS was developed to analyze surface water samples collected from East Palestine, Ohio, U.S. in the weeks after a train derailment and subsequent chemical spill and burn.