Browsing by Subject "VOCs"
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Item Effect of relative humidity on chemical off-gassing in residences(2011-05) Nnadili, Miriam Nchekwubechukwn; Corsi, Richard L.; Kinney, Kerry A.Relative humidity (RH) is an important parameter associated with occupant comfort in buildings. However, the effects of RH on indoor source off-gassing and interactions between air pollutants and indoor materials are poorly understood. For this study, air samples were collected in residential buildings to characterize “background” concentrations of volatile organic compounds (VOCs) in air. The interior space was then humidified for several hours prior to collection of another air sample to characterize the effects of increased RH on VOC concentrations. Samples were analyzed by GC/FID with abundance “binning” by elution time. Some samples were also analyzed using GC/MS to identify specific VOCs. Results indicate that increasing RH is associated with increases in VOC concentrations in residential indoor air. Many of the chemicals that show enhanced off-gassing are associated with architectural coating, moth repellents, and cleaning agents. The results of this study are novel and may have implications with respect to health effects associated with damp buildings and increased respiratory effects of children during sleep in bedrooms with elevated RH.Item Indoor air quality in retail stores(2011-05) Rhodes, Joshua Daniel; Siegel, Jeffrey A.; Xu, YingRetail stores are understudied given the energy, occupant health, and potential sales impacts associated with poor indoor air quality (IAQ). There is also evidence of elevated pollutants in retail environments. This thesis is an exploration of the indoor air quality of retail stores. The first section of this thesis is a literature review on field investigations of the indoor air quality in retail buildings. Sixteen investigations report different measurements in 17 specific types of retail environments. Measurements vary depending on the specific investigation, but include VOCs, SVOCs, particles, microbiological species, and radon. When reported, indoor to outdoor ratios of almost all pollutants are greater than unity, suggesting the importance of indoor sources in retail environments. The second section of this thesis is an analysis of the whole store net emission factor for different retail environments. From the types of pollutants found in the retail store investigations, VOCs were the only pollutant group studied frequently enough to merit this analysis. The final section is an analysis of the potential for pollutant remediation strategies. Two methods, increasing air change rate and air cleaning, are considered with an analysis of the energy penalties associated with each.Item Performance assessment of TVOC sensors used in consumer-grade air quality monitors(2021-09-27) Bastami, Sepehr; Nagy, Gyorgy Zoltan; Kinney, KerryIndoor Air Quality (IAQ) has a direct impact on overall occupant health, especially respiratory and neural health. To ensure adequate indoor air quality, we must monitor the air by regularly sampling for pollutants of concern. One important category of air pollutants is VOCs: Volatile Organic Compounds. Some VOCs may be toxic at low concentrations while others require prolonged exposure at high concentrations to become a concern. Traditionally, measuring VOCs accurately has been prohibitively expensive and/or complicated. Recently, consumer-grade air quality monitors have been advertised as affordable counter parts to the expensive and complicated research-grade monitors and sensors. We studied the performance of a unique category of Total Volatile Organic Compounds sensor called a CMOS sensor. We assessed the performance of two brands of TVOC sensors used in three consumer-grade air quality monitors. We conducted a total of 5 experiments, 3 in a real home environment and 2 in a laboratory setting using a state-of-the-art air quality sampling device called the Vocus PTR-Tof. The consumer grade devices tend to exhibit some degree of uniformity in their patterns in response to pollution events, however, they can often deviate from one another in measuring actual concentration levels. The CMOS sensors studied suffer from a range of persistent challenges inherent to the CMOS technology, such as sensitivity and selectivity limitations. While improvements continue, more research is required to determine the extent to which these sensors may be useful and whether they can reliably and reasonably be used to assess indoor air qualityItem Studies on particle resuspension, infant exposure, and the sleep microenvironment(2015-08) Boor, Brandon Emil; Xu, Ying (Assistant professor); Novoselac, Atila; Corsi, Richard L; Hildebrandt Ruiz, Lea; Järnström, Helena; Howard Reed, CynthiaUnderstanding the transport of particulate and gaseous indoor air pollutants from source to exposure is paramount to improve our understanding of the complexities of the built environments in which we spend the majority of our time. This dissertation offers new insights on particle resuspension from indoor surfaces, infant exposure to organic contaminants released from crib mattresses, and the dynamics of pollutant transport and human exposure while sleeping. Particle resuspension is the physical process by which settled particles detach from a surface and become airborne through application of various aerodynamic and mechanical removal forces. Resuspension is an important indoor source of coarse mode particles (> 1 µm in diameter) and can be a source mechanism for biological matter and organic contaminants that accumulate in house dust. Settled dust deposits on indoor surfaces can vary considerably in their structure and mass loading, yet little is known as to how these parameters affect resuspension. Through wind tunnel experiments, this research demonstrates that the deposit structure (monolayer or multilayer) can have a significant impact on the number of particles that aerodynamically resuspend. Furthermore, this dissertation presents the first full-scale experimental chamber study to show that human body movements in bed can resuspend settled mattress dust particles. An indoor aerosol model was utilized to provide a mechanistic understanding of the impact of movement intensity, surface vibrations, bedroom ventilation rate, and dust loading on the resuspension flux and intake fraction of resuspended particles. Infants spend most of their time sleeping and are likely to be exposed to elevated concentrations of chemicals released from their crib mattresses. Through a combination of chamber experiments and solvent extractions, this research shows that infant crib mattresses can emit a variety of volatile organic compounds (VOCs) and contain numerous chemical additives, including phthalate and alternative plasticizers, flame retardants, and unreacted isocyanates. Additionally, this study discovered that infants are exposed to approximately twice the concentrations of VOCs in their breathing zones as compared to the bulk bedroom air, due to their close proximity to the source.