Browsing by Subject "Indoor air pollution"
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Item Essays on the economics of indoor and outdoor environments(2009-08) Briggs, Ronald Joseph; Williams, Roberton C., 1972-This dissertation consists of three chapters on questions in Environmental Economics, addressing policy and health issues in indoor and outdoor environments. In the first chapter, I explores price and quantity policy solutions to externalities that arise from private decisions made over time, focusing on resource extraction as a specific example. In the U.S., mining causes more pollution than any other single industry. I show how tax policy can optimally address a flow externality associated with resource extraction when the policymaker faces asymmetric information in the short run. Chapter 2 investigates whether ordinary exposure to a common indoor air pollutant—Nitrogen Dioxide (NO₂)—affects respiratory health. About 40 percent of occupied homes in the U.S. use gas stoves for cooking, which produce NO₂ as a byproduct of combustion (US Census, 2006), and peak concentrations in homes may reach above 900 ppb when a gas stove is used for cooking (Dennekamp et al., 2001). Permanent or fatal lung damage occurs at NO₂ concentrations greater than 1000 ppb (Samet and Utell, 1990). Previous studies find mixed evidence of negative effects from indoor NO₂ (Basu and Samet, 1999), but exposure may be endogenous in these analyses. I address this problem by developing a physical model of indoor NO₂ concentrations that depends on ventilation decisions and housing characteristics and estimate it using data from the third wave of the National Health and Nutrition Examination Survey. In every model I consider, I find no significant effects of gas stoves on respiratory outcomes. In the final chapter, I combine data on state and local tobacco control ordinances from Americans for Non-smokers Rights Tobacco US Tobacco Control Laws Database with a sample of 35 million births in the U.S. to examine the impact of smoking bans on birth weight and related outcomes. Using difference-in-difference techniques, I identify the effects of state bans net of local bans, as well as the effects of local bans net of state bans. The results suggest less restrictive bans do more to improve birth outcomes than “100% smokefree” bans do, particularly in urban settings.Item Fine particle formation in indoor environments: levels, influencing factors and implications(2002) Sarwar, Md Golam; Corsi, Richard L.; Allen, David T.Experiments were conducted in an 11-m 3 stainless steel chamber to investigate secondary particle formation/growth in indoor environments. Experimental results indicate that rapid particle growth occurs due to homogeneous reactions between ozone and terpenes, and subsequent gas-to-particle partitioning of reaction products. Experimental results also indicate that many consumer products can emit significant amounts of terpenes that can serve as precursors to the formation of indoor fine particles. A new Indoor Chemistry and Exposure Model (ICEM) was used to predict dynamic particle mass concentrations based on detailed homogeneous chemical mechanisms and partitioning of semi-volatile products to particles. The ICEM allows for the simulation of air exchange processes, indoor emissions, chemical reactions, deposition, and variations in outdoor air quality. Predicted indoor secondary particle mass concentrations are in good agreement with experimental results. Both experimental and model results suggest that secondary particle mass concentrations increase significantly at lower building air exchange rates. This result is significant given a continuing trend toward building weatherization for purposes of energy conservation. Predicted indoor secondary particle concentrations increase with lower temperatures, higher outdoor particle levels, higher outdoor ozone levels, and higher indoor terpene emission rates. Indoor secondary particle concentrations resulting from reactions between ozone that originates outdoors and terpenes that originate from indoor sources can be higher than indoor particle concentrations resulting from the transport of outdoor particles. If ozone generation air “purifiers” and elevated terpene levels are simultaneously present in indoor environments, the resulting indoor secondary particle mass concentrations can exceed 65 mg/m3 . The implications of this study are significant. It appears that it is now possible to reasonably simulate complex indoor chemistry and particle growth dynamics using a state-of-the-art model (ICEM). More importantly, it appears that under some conditions, indoor air chemistry can lead to significant increases in human exposure to fine particles. Such exposure could be reduced by avoiding indoor sources of ozone, e.g., from ozone generators marketed as air “purifiers”, or by reducing the use of consumer products that contain terpenes, especially during the summer ozone season.Item The capability of a solid sorbent desiccant unit at removing selected indoor air quality-relate microorganisms from the air(Texas Tech University, 2004-08) Larrañaga, Michael DavidThroughout history, diverse cultures and societies have appreciated the importance of a clean and healthy indoor environment. In western societies today, most people spend greater than 90% of their time indoors. Reports involving buildings with indoor air-related problems have appeared increasingly in the medical and scientific literature, although this problem has been with humans for centuries. Sick building syndrome (SBS), a common term for explaining symptoms that result from individuals' exposure to poor indoor air quality (IAQ), was first recognized as an important problem affecting occupants in certain buildings in 1982. The presence of moisture, fungi, spores, and fungal growth in sick buildings has become consistently associated with SBS. Poorly maintained heating, ventilation, and air conditioning (EIVAC) systems have been recognized as sources of microorganisms, including fungi. Undesirable moisture levels and fungal growth indoors represent a public health concern inadequately addressed by building, health, or housing codes. Drying the ventilation air via the honeycomb wheel desiccant based cooling is a cost effective method of humidity control and removes statistically significant concentrations of IAQ-related microorganisms from the air. Controlling humidity is crucial for human comfort, minimizing adverse health effects associated with high humidity and maximizing the structural integrity of buildings. Several authors have stated that the use of active desiccants enhances the quality of the indoor air by helping to maintain comfort criteria (temperature, humidity, and ventilation, removing particulates and bioaerosols from the air, and removing chemical pollutants from the air. The capabilities of a rotary wheel solid-desiccant dehumidifier at removing selected IAQ-related fungal organisms from the airstream were quantified at temperatures ranging from GO^F to 36Q°F at 100°F intervals. Average removal efficiencies for viable concentrations of spores ranged from 42%-98% for Aspergillus niger, Cladosporium cladosporioides, and Penicillium chrysogenum at the four temperature settings. Average removal efficiencies for total spore concentrations ranged from 30%-95% for the same organisms and temperature settings. The results of this study show that utilizing a rotating honeycomb desiccant apparatus in conjunction with conventional air conditioning can significantly reduce the airborne concentrations of IAQ-related microorganisms delivered to the indoor air.