This thesis presents the results of a research project that involved laboratory experimentation for gathering data on how the concentration of a dense gas disperses in indoor air. A box was built and designed as a model of a typical indoor environment and a dense contaminant, carbon dioxide, was injected into the box at a known flow rate through either a high or a low injection port. The gases left the box through either a high or a low exit port. The concentration of the contaminant inside the box was measured with an indoor air quality monitor at sampling ports at different locations and at different times during the experiments. The time and place dependent data were organized to observe the pattern of dispersion of a dense indoor air contaminant. It was determined that CO2 tended to sink down and move away from the point of injection at lower elevations, while gradually diffusing upwards. It was concluded that the dispersion of carbon dioxide in the box was driven mainly by the density gradient and to a less extent by diffusivity.

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Background: Exposure to indoor air pollutants has been associated with poorer respiratory health in children. This study investigates the respiratory health of Malaysian schoolchildren in relation to indoor air pollution. Methods: This cross-sectional study was conducted among 2,164 schoolchildren aged 10-11 years in urban and semi-rural schools. Parents completed a questionnaire and concentrations of air pollutants were measured in schools. SHS exposure was assessed using salivary cotinine. Results: The WHO Air Quality Guideline for PM2.5 was exceeded for most of the semi-rural schools while almost all of the urban schools exceeded the annual exposure limit for NO2. The Geometric Mean salivary cotinine concentrations for non-smoking schoolchildren were 0.47 ng/ml. The 3 main predictors of nocturnal cough were the presence of a current smoker at home (OR 1.97; 95% CI: 1.31-2.96), the absence of exhaust system in the kitchen (OR 1.67; 95% CI: 1.03-2.68) and the use of air conditioning (OR 3.10; 95% CI: 1.37-5.71). Exposure to SHS of ≥4 hours per day (OR 2.53; 95% CI: 1.55-4.14) explained approximately 6.0% of the likelihood of reporting doctor-diagnosed asthma. For the measure of asthma severity, NO2 and log average family size were the 2 predictors of limited speech during wheeze; NO2 concentrations of >50 μg/m3 contributes an OR of 5.98 (95% CI: 1.02-34.9) and log average family size with an OR of 14.6 (95% CI: 1.70-126). Conclusion: This study has identified that many Malaysian schoolchildren experience exposure to air pollution indoors that exceeds WHO guidance limits for several pollutants. There was no clear relationship between traffic-generated air pollutants and children’s respiratory health but there was a strong relationship between the number of hours children were exposed to SHS and asthma. There is a need for increased enforcement of existing smoke-free legislation and policies to reduce children’s exposure to SHS.

ABSTRACT Indoor air pollution has been associated with acute lower respiratory infections amongst children less than five years old in developing countries. Very little is known about the potential role of behavioural change in reducing child indoor air pollution exposure. This thesis explores three questions: did people change their behaviours following exposure to an intervention that promoted the health benefits of behavioural change? Were changes in behaviour attributable to the intervention? What were the motivations and barriers to behavioural change? The evaluation included a quantitative and a qualitative study. The quantitative study utilised a quasiexperimental before-after design amongst an intervention village (n=98 households). Results were compared to a similar control village (n=121) that did not receive the intervention. Baseline data were collected during winter 2003 and follow-up data were collected during winter 2004 (12 months later). A qualitative evaluation, using two rounds of 4 focus group interviews each, was used to answer questions that emerged from the quantitative study. Indoor air quality - PM10, CO and CO (measured on the youngest child) - were measured over a 24 hour period in randomly selected households before and after the intervention in the intervention (n=36) and control (n=38) groups. After adjusting for confounding factors, there was no statistical association between having the received the intervention and the likelihood of burning outdoors at follow-up (OR=1.16; 95% CI 0.6-1.8). Indoor air quality data showed significant median reductions in PM10 (94-96%), CO (85-97%) and CO (child) (83- 95%) amongst households that burned outdoors compared to those that burned indoors. Results from the qualitative study suggest that motivations for outdoor burning included: health considerations, reaction to participating in the study, reduced drudgery and prestige. Barriers to outdoor burning included the need for space heating during winter, perceptions of low indoor air pollution risk and gender relations. This study highlights the potential for exposure reduction through behavioural change and is original for three reasons. It is the first behavioural intervention study designed to reduce indoor air pollution in a rural African setting. Secondly, it is the first intervention study in the indoor air pollution field to identify the factors that influenced behavioural change. Thirdly, it is one of the first studies to align debates about behavioural change in the field of indoor air pollution with those in the broader environmental health promotion literature.

Thesis (Ph. D.)--University of Texas Health Science Center at Houston, 2005. / Includes bibliographical references (leaves 376-393). Also available online via the Texas Medical Center website (http://digitalcommons.library.tmc.edu/).

Many chemicals off-gas or leech into indoor environments from sources such as consumer products, furnishings, and building materials. An understanding of the pathways from the sources to human exposure is vital in order to implement control strategies and lower exposure. Objects containing Brominated flame retardants (BFRs), one class of semivolatile organic compounds (SVOCs), burn more slowly during combustion. BFRs, especially polybrominated diphenyl ethers (PBDEs), are used in electronic devices including casings and circuit boards. Heat from internal circuitry increases the BFR vapor pressure and the partition coefficient, enhancing its transport out of the substrate and into the indoor environment. In this work, a computer tower in an office setting provides a case study to examine the emissions of, and exposure to, PBDEs. the case of a computer tower, the cooling fan increases the mass transfer coefficient, further increasing emissions. During computer use, the emission rate of PBDEs from the interior of the case is more than double the emission rate from the exterior of the case due to elevated internal temperatures and higher mass transfer due to the cooling fan. The concentration of PBDEs in the room air increases 40 - 80% for every 5°C increase inside the computer case, depending on the PBDE congener. Such enhanced emissions are a concern since recent studies have shown adverse health effects of PBDEs on human health. The major contributions of this work are: A model was developed that is useful for SVOC emissions for various heat and mass transfer situations, including diffusion through the slab and convective boundary conditions on each side of the slab, which may be simplified if the situation warrants; A systematic propagation of the uncertainties and variability of the model parameters was accomplished by using a Monte Carlo method for the input of the parameters into the model; A polydisperse indoor particle distribution was used as a sink, identifying the size-discretized particle phase PBDE concentration; An exposure assessment showed that the inhalation pathway for PBDEs in the gas and particulate phases is relevant and that the particulate phase exposure is dominant. / text

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published_or_final_version / Architecture / Master / Master of Philosophy

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