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.

Mycotoxins are secondary metabolites produced by many fungal species. Health effects induced by the ingestion of these substances are well documented and some mycotoxins are now regulated for their maximum tolerable levels in foods. However, other routes of exposure to these contaminants are possible. Thus, if irritating or allergenic reactions related to the inhalation of fungal spores or mycelial fragments have been demonstrated, inhalation of mycotoxins is also suspected to be causing certain respiratory disorders or certain pathologies. Indeed, mycotoxins can be found in spores but also on finer particles which are easily aerosolized and therefore likely to be inhaled. However, data on the hazard associated with human exposure to mycotoxins by inhalation are still very fragmented. In this context, our main objective was to characterize the aerosolization of mycotoxins during the colonization of different materials encountered in indoor environments by toxinogenic molds. First we studied growth and production of mycotoxins during the colonization of building materials (wallpaper, painted fiberglass wallpaper, vinyl wallpaper, fir, fiberglass) by three fungal species of interest: Aspergillus versicolor, Penicillium brevicompactum, Stachybotrys chartarum. These species were chosen because of their frequent presence in indoor environments and their diverse mycelial organization. In addition, these three species produce different toxins: sterigmatocystin, mycophenolic acid and macrocyclic trichothecenes for A. versicolor, P. brevicompactum and S. chartarum, respectively. These studies have shown that, during their development on tested materials, three species produce mycotoxins. The most favorable material for fungal development and toxinogenesis is wallpaper. Mycophenolic acid, sterigmatocystin and macrocyclic trichothecenes can thus be produced at levels of 1.8, 112.1 and 27.8 mg/m2, respectively, on this material. These toxins can then be partially aerosolized. We have shown that aerosolization depends on species and their mycelial structure, but also on culture conditions and airflow. This transfer to air is nevertheless observed after aeraulic solicitations which can be easily encountered in indoor environments because theycorrespond to the movement of people in a room (0.3 m/s), speed of air in ceiling diffusers (2 m/s), slamming doors or air drafts when opening windows(6 m/s). P. brevicompactum showed to be the easiest to aerosolize. The major part of the aerosols’ toxic charge is found in particles whose size corresponds to that of spores or mycelial fragments. However, for macrocyclic trichothecenes, toxins were also found in particles smaller than spores, which could easily be inhaled by occupants and penetrate deep into the respiratory tract. In order to better characterize the actual hazard associated with inhalation of these compounds, cytotoxicity studies have been performed using lung cells and comparing with results observed on digestive cells. Pulmonary toxicity is comparable to that observed in digestive cells. Macrocyclic trichothecenes are much more toxic than other tested toxins with IC50 in order of ng/ml. In parallel, we analyzed the VOCs specifically produced during active mycotoxinogenesis in order to identify potential biomarkers of the actual production of mycotoxins that could be used as tools for monitoring of indoor environments. Unfortunately, this approach has not, for the moment, led to the identification of specific targets. In the end, we evaluated the persistence of these contaminants during application of bleach, the most frequently used decontamination process. We have shown that a normal cleaning procedure allows only partial removal of mold.

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

Microorganisms found in the indoor environment of retail stores are not well studied, despite potentially serious human exposure implications. In this study, filters from central heating, ventilation, and air-conditioning (HVAC) units were used to collect a time-integrated sample of the airborne indoor microbiome in 14 U.S. retail stores. The microbial communities recovered from the filter dust samples were analyzed with pyrosequencing to characterize the fungal and bacterial microbiome present. The objectives of this work were to: (1) characterize the microbial communities present in retail stores, (2) delineate relationships between the indoor microbiome and building or environmental parameters, and (3) evaluate the use of HVAC filter dust as a sample location for indoor microbial investigations. The microbiome in retail stores was observed to be diverse with 4,771 and 1,577 unique operational taxonomic units for bacteria and fungi, respectively. The diverse microbial community detected over time in the same store could not be fully explained by seasonal trends. That indicates that even when utilizing a long-term sampling approach like HVAC filter samples, the indoor microbiome cannot be completely characterized by a single sampling event. The bacterial community in retail stores was influenced by the outdoor microbiome and microbiota commonly associated with human skin. Physical location of the retail stores had some influence on the bacterial microbial community present and strongly impacted the fungal community recovered. Air exchange rate did not influence the observed bacterial or fungal communities. In a comparison to five other indoor air samplers, passive samplers including HVAC filter dust and settled dust captured a higher diversity of the microbial community. The collection of a more diverse sample may allow detection of potentially pathogenic microorganisms. However, there was significant difference in the microbial community structures recovered between samplers in the same sampling event which suggests sampling methodology has an impact on the inferred microbiome recovered. The overall results from this study indicate that retail stores harbor a diverse microbial community that varies over time. / text

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published_or_final_version / Architecture / Master / Master of Philosophy

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