Radon is a naturally occurring radioactive element in the 238U decay series that is found in high concentrations in certain geological formations such as Caves. Exposure to high concentrations of radon has been positively linked to the incidence<br /> of lung cancer. This study used Electret ion chambers and the RAD7 continuous radon monitor to measure radon concentrations in the Cango Caves in the Western Cape Province, South Africa. Measurements were taken during summer i.e. February 2004 and March 2005. The results for the radon activity concentrations range from the minimum of<br /> about 800 Bq.m-3 to a maximum of 2600 Bq.m-3. The two techniques give very similar results, though the Electret ion chamber results appear to be consistently higher by a few percent where measurements were taken at the same locations. A<br /> mathematical model has been developed to investigate the radon concentrations in the Cave. Diffusion and ventilation have been considered as mechanisms for explaining the distribution of radon concentrations. The ventilation rate in the Cave has been estimated under certain assumptions, and it is found to be about 7 &times / 10&minus / 6 s&minus / 1 for the Van Zyl hall which is the first large chamber in the Cave. The radon concentration increases as one goes deeper into the Cave, but then becomes fairly constant for the deeper parts. The annual effective dose that the guides are exposed to in the Cave as a result of the radon concentrations, depends strongly on the time that they spend in the Cave and in which, halls they spend most of their time in the Cave. The initial results indicate an annual effective dose of 4-10 mSv, but this needs to be further investigated.

Indoor air quality has become an important health concern due to the number of indoor pollutants and the realization that even minimal exposures to volatile organic compounds may produce direct or indirect adverse health outcomes. Young people are most vulnerable to these poisonous chemicals as they spend much of their times indoors at homes, schools, nurseries and in day care centers. Exposure to volatile organic compounds indoors has been related to asthma and other respiratory symptoms. The adverse effects of air pollution on respiratory health in South Durban have been described in a number of studies. In 2000, a study in the South Durban Basin at Settlers Primary School demonstrated both a high prevalence of respiratory diseases amongst schoolchildren as well as an association between ambient air pollutants and other adverse health outcomes. The South Durban Health Study subsequently undertook a health risk assessment and an epidemiological study investigating this association further on behalf of the eThekwini Municipality. The study highlighted that relatively moderate ambient concentration of N02, NO, PMIO and S02 were strongly and significantly associated with a reduction in lung function among children with persistent asthma. Moreover, attending primary school in South Durban was significantly associated with increased risk from persistent asthma when compared to schools in North Durban. METHODS The descriptive study measured the total volatile organic compound levels within selected homes and schools of asthmatic children in South and North Durban. Recommendations for reducing or mitigating indoor total volatile organic compound exposures were made. The study involved a secondary analysis of data obtained from the South Durban Health Study. The monitoring for total volatile organic compounds within homes and classrooms was undertaken using passive samplers during a 72-hour period and analyzed using a gaschromatography/ mass spectrometry method. Temperature and humidity was assessed using temperature and humidity sensors. Statistical analysis was performed using SPSS version 13. The dataset comprised 140 total volatile organic compound samples from homes and 14 from classrooms. Total volatile organic compounds were measured in microgram per cubic meter (g/m3), temperature in degrees Celsius and relative humidity in percentage of moisture. RESULTS Total volatile organic compounds with levels in households ranging from 17g/m3 to 1440g/m3 and in classrooms ranging from 48g/m3 to 5292g/m3 were measured. The mean levels detected were significantly different in homes and classrooms / Thesis (MMed.)-University of KwaZulu-Natal, Durban, 2008.

There is increasing recognition of the links between air pollution and human health. Epidemiological studies have shown that there are numerous air pollutants that are associated with indoor energy use and with the production processes of industries, and most represent some sort of health implication. However, in-depth and fundamental knowledge of the health impact relationship of most pollutants is limited. This research evaluates the socio-economic and spatial aspects of the health implications of air pollution in Richards Bay (located 200 km north of Durban), KwaZulu-Natal. The research explores community perceptions and complaints relating to human health impacts emanating from air pollution in Richards Bay. The research is informed by a multi-conceptual framework (political economy incorporating political ecology, place perspectives and environmental justice) which influenced the methods chosen in conducting the research. Standard quantitative and qualitative methods were employed in the study to generate data relating to the research objectives. The process of triangulation which is the use of multiple methods that cuts across the qualitativequantitative divide was used. The various sources of information validate and clarify data by deepening and widening an understanding of the main issues under examination. The research was implemented in various communities in Richards Bay that reflect socioeconomic differences, which contributes significantly to ascertain whether health impacts are differentially experienced by different socio-economic groups. Furthermore, the research cross-tabulated experiences, perceptions and coping strategies of different socio-economic groups in the area, especially in relation to upper, middle and lower income clusters. The spatial aspect of the research (mapping of key social and health variables) is a major contribution of this research, which draws from the field of medical geography. Information on the main residential areas was illicitied from documents providing background details on Richards Bay. A purposive sampling approach was adopted to identify the seven communities, namely, Alton, Aquadene/ Brackenham, Arboretum, Meer-en-See, Empangeni Rail, Nseleni and Umhlathuze. Simple random point sampling was used to identify the households within the communities. The number of households in each community was determined using proportionate sampling. Four hundred and seventy nine housholds (479) were interviewed which was deemed to be a statistically relevant sampling size at a 95% confidence level. The study findings indicate that the lower income areas (Nseleni, Empangeni Rail and Umhlathuze) and the middle income areas (Aquadene/ Brackenham and Arboretum) have a more youthful population with a significant number being children, while the upper income areas (Alton and Meer en See) have a more elderly population. A similar trend was also found in relation to household size. There are clearly major variations in household income and employment types in Richards Bay, linked in part to the geographical location of communities based on economic and racial groups. Lower earning respondents were located mostly in the lower status areas which were classified as predominantly African populated areas as per the historical race classification and apartheid segregated areas. More than half of the respondents indicated that industrial smoke was the cause of their present health conditions. Other stated reasons were wide ranging and therefore there was no discernible pattern that emerged in relation to the causes for poor health experienced by the affected household member. However, the data did show that more respondents living in middle/ upper income areas identified causes. Reported health conditions include allergies (30.9%), coughing (29.8%), wheezing (25.5%), chest pains (18.4%) and asthmatic bronchitis/ asthma (17.7%). With regards to health care, the findings from the study show that the economically better off communities (Alton, Aquadene/ Brackenham, Arboretum and Meer en See) used the private, more expensive health care sector while generally households in lower income areas tend to rely on public or traditional health care facilities. An interesting finding was that most respondents rate their general health status as either excellent, good (more respondents from the middle/ upper income areas than the lower income areas) or satisfactory (more respondents from Umhlathuze). A large majority of the respondents reported air pollution as the main problem that is associated with industries in Richards Bay while the health impacts of pollutants from the industries manufacturing processes was the second main cause. The areas deemed to be the most polluted were generally in or in close proximity to the industrial area or the port area. Lower income areas tendered to be most polluted, according to respondents residing in these areas or who lived in similar low income areas. The majority of respondents were found to be living in dwellings/ households made from dwellings constructed with brick and asbestos, brick and zinc, stone and other traditional materials which is indicative of housing in the poorer communities who live in informal dwellings/ households and may be a causal contributing factor of the poor health status of these communities. The participatory mapping exercise conducted during the focus group discussion revealed that participants identified the industrial areas (including the port and surrounds) as the most polluted areas. Areas outside Richards Bay were considered to be the least polluted areas. The research findings indicate that there are a complex mix of socio-economic, environmental and spatial dynamics that influence air pollution and health impacts. Thus, health issues in the context of widespread air pollution concerns are linked to social, political and environmental aspects that require urgent attention. Air pollution and health impacts remain major concerns in many parts of the world, especially in areas of high levels of industrial development such as Richards Bay. The results of this research, therefore supports the findings of other researchers who reveal that communities/ neighborhoods of lower income status are most likely to bear the brunt of negative impacts and that air pollution from indoor uses of energy, behavioral factors such as cigarette smoking and industrial processes contribute to an individual’s/ community’s quality of life. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2013.

Radon is a naturally occurring radioactive element in the 238U decay series that is found in high concentrations in certain geological formations such as Caves. Exposure to high concentrations of radon has been positively linked to the incidence<br /> of lung cancer. This study used Electret ion chambers and the RAD7 continuous radon monitor to measure radon concentrations in the Cango Caves in the Western Cape Province, South Africa. Measurements were taken during summer i.e. February 2004 and March 2005. The results for the radon activity concentrations range from the minimum of<br /> about 800 Bq.m-3 to a maximum of 2600 Bq.m-3. The two techniques give very similar results, though the Electret ion chamber results appear to be consistently higher by a few percent where measurements were taken at the same locations. A<br /> mathematical model has been developed to investigate the radon concentrations in the Cave. Diffusion and ventilation have been considered as mechanisms for explaining the distribution of radon concentrations. The ventilation rate in the Cave has been estimated under certain assumptions, and it is found to be about 7 &times / 10&minus / 6 s&minus / 1 for the Van Zyl hall which is the first large chamber in the Cave. The radon concentration increases as one goes deeper into the Cave, but then becomes fairly constant for the deeper parts. The annual effective dose that the guides are exposed to in the Cave as a result of the radon concentrations, depends strongly on the time that they spend in the Cave and in which, halls they spend most of their time in the Cave. The initial results indicate an annual effective dose of 4-10 mSv, but this needs to be further investigated.

Recent and past events in the South Durban Basin (SDB) have highlighted the possible connection between perceived air pollution concerns and deteriorating health. The aim of this study is to explore how the SDB community perceives air pollution and if this can be related to some of the health problems that are experienced in these communities. The ultimate aim is to determine whether the respondents connect air pollution to specific illnesses and also how they perceive the actions used to combat air pollution and its negative health impacts. This information is gathered through a questionnaire conducted in various study areas both within and outside the SDB, then compared with demographic variables. This is done to determine if perception is related to direct industrial activity or if there are other factors influencing results. Variables such as race and level of education had little impact on the results. The results showed that areas within the SDB experience a high neighborhood satisfaction despite the current general belief of air pollution being connected to ill health. The control areas outside of the SDB support theories of gender and race and its relationship to air pollution, currently presented by researchers in the perception field. Strong associations’ do exist between general environmental satisfaction and gender. Perception of current legal enforcement is exerting a strong effect on air pollution perception formation. Vitally important is the connection of daily concrete experiences of air pollution with the lack of transparency and communication between industry and communities. It is resulting in the current perception of illness being connected to tangible air pollution. The aim is to further future studies on establishing links between health and air quality. Gaining insight from the study of public risk perceptions based on local knowledge and experience in particular places, will help shape the role of environmental policy and management response systems. / Geography / M.A. (Geography)

Applied economics studies target effects that can be relatively small. This dissertation delves into some statistical obstacles to the accurate estimation of such effects, with a particular focus on the concepts of statistical power and exaggeration---imprecise studies tend to produce inflated estimates of the effect of interest. It explores implications of low power and exaggeration that are specific to applied economics studies and their design. Through the example of studies on the acute health effects of air pollution, the first chapter identifies tangible drivers of exaggeration that extend beyond small effects and a limited sample size. This analysis uncovers an overarching mechanism, studied in Chapter 2, that induces exaggeration when using causal identification strategies. This subsequent chapter emphasizes that causal approaches only focus on a subset of the variation---the exogenous part---reducing the precision of the study and increasing risks of exaggeration. The final chapter further broadens the discussion to analyze design choices in light of the multiple goals of causal inference studies; these studies aim not only to identify an average effect but also differentiated effects across subgroups, as well as producing insights that extend beyond the population considered. Overall, this dissertation underlines the manifold implications of design choices on non-experimental economic studies, with the aim of contributing to more accurate estimations of effects to better inform policymaking.

The COVID-19 pandemic elucidated geographical disparities in COVID-19 burden on a globalscale. Geographical disparities in adverse COVID-19 outcomes may suggest population-level drivers of disease, such as environmental exposures. Epidemiological literature provides strong evidence that greater exposure to ambient air pollution, an environmental exposure, is associated with a greater risk of COVID-19 hospitalization and fatality. The pathways by which ambient air pollution exposure influences adverse COVID-19 outcomes are currently unknown. I propose that cardiovascular morbidity is relevant in this pathway, given that cardiovascular morbidity is a predominant risk factor of adverse COVID-19 outcomes, and there are strong and consistent associations between air pollution and cardiovascular morbidity. I suggest that the role of cardiovascular morbidity will be different for historical air pollution (period > 30 days) and short-term air pollution (period < 30 days). By proposing clear causal structures for the relationship between air pollution and adverse COVID-19 outcomes, we can explicate how air pollution leads to greater COVID-19 burden and address the larger goal of reducing geographic disparities in adverse COVID-19 outcomes. This dissertation is comprised of three specific aims. For the first aim, I performed a systematic review of the literature that examined the relationship between ambient air pollution and individual-level adverse COVID-19 outcomes. I identified if and how researchers conceptualized the causal role of comorbidities, specifically cardiovascular morbidities, in the relationship between air pollution and adverse COVID-19 outcomes. For the second aim, I examined if cardiovascular morbidity mediates the relationship between historical air pollution and adverse COVID-19 outcomes. For the third aim, I examined if there was evidence of synergistic interaction between short-term air pollution and cardiovascular morbidity in influencing the risk of adverse COVID-19 outcomes, suggesting that the effect of both short-term air pollution and cardiovascular morbidity on adverse COVID-19 is greater than the sum of the individual effects. In conducting the first aim, I used Covidence, a software used to manage systematic reviewstudies, to identify studies that examined the relationship between ambient air pollution exposure and individual-level adverse COVID-19, using the Embase, MEDLINE, and Web of Science databases. In conducting the empirical aims, I used a retrospective cohort study design using INSIGHT-Clinical Research Network (CRN) data, a harmonized repository of inpatient electronic health records in New York City (NYC) across metropolitan healthcare systems (3/1/2020-2/28/2021). INSIGHT-CRN included data pertaining to sociodemographics, diagnoses, outcomes, and residential ZIP Code to link air pollution exposure. For the second aim, I used the New York City Community Air Survey (NYCCAS) to estimate historical air pollution exposure to particulate matter (PM2.5), black carbon (BC), nitrogen dioxide (NO₂), and ozone (O₃) on a ZIP Code level (2009-2019). For the third aim, I used the 2020 Environmental Protection Agency (EPA) Community Multiscale Air Quality (CMAQ) downscaler modeled data, which estimated 2020 daily exposure to PM2.5 and O3 on a census tract level. I aggregated the census tract data to ZIP Code using a spatial weighting approach and estimated short-term air pollution as a 7-day average of daily PM2.5 and O3 exposure prior to patient hospitalization. For the first aim, the systematic review included 42 studies that examined the relationship between ambient air pollution, such as exposures to PM2.5, NO₂, and O₃, and individual-level adverse COVID-19, such as hospitalization, intensive care unit (ICU) admission, intensive respiratory support (IRS), and fatality. The studies were primarily retrospective cohort study designs, and were conducted in the United States and Europe (2020 to 2021). The majority of studies adjusted for cardiovascular morbidity without causal role specification, whereas some studies identified cardiovascular morbidity as a mediator or an effect modifier. For the second aim, I found evidence of cardiovascular morbidity mediating the relationship between historical air pollution and risk of acute respiratory distress syndrome (ARDS), dialysis use, ventilation use, and COVID-19 fatality, but not risk of pneumonia from March to June 2020, within areas of greater hospital catchment. Indirect effects suggest that historical air pollution increases the risk of atrial fibrillation and myocardial infarction, which increases risk of adverse COVID-19. For the third aim, I found evidence of synergistic interaction between short-term PM2.5 and presence of cardiovascular morbidities for only risk of COVID-19 pneumonia, in the latter half of 2020. Overall, there was evidence that cardiovascular morbidity mediates the relationship betweenhistorical air pollution and more severe COVID-19 outcomes, while cardiovascular morbidity synergistically interacts with short-term air pollution for risk of acute respiratory infections, such as pneumonia. This dissertation assesses the pathways by which air pollution may influence risk of adverse COVID-19, in better examining the causal role of cardiovascular morbidity. Knowledge gained could be used to mitigate population-level vulnerabilities to air pollution, and encourage population-level pandemic preparedness in the future.

研究背景：顆性空氣污染物（PM₁₀）的危害作用已經為許多病學研究所證實。有學者認為，空氣動學直徑小於2.5 微米的細顆（PM₂.₅）和空氣動學直徑介於2.5 和10 微米之間的粗顆（PMc）屬於種同的污染物，應當分別測。區分粗、細顆的健康效應將為今後分別制訂有關粗、細顆的空氣質標準提供依據。同時，空氣污染物是由顆污染物和氣態污染物構成的複雜混合物，二者之間存在一定程上的合或交互作用。 / 研究目的：以每天心血管系統、呼吸系統疾病急性入院人為研究結局，區別估計顆污染物PM₁₀ 中粗、細顆的健康危害作用，并探討PM₁₀與氣態污染物（二氧化氮，NO₂；二氧化，SO₂；臭氧，O₃）的交互作用。 / 研究方法：收集香港1998 1 月至2007 12 月每天心腦血管疾病、呼吸系統疾病急性入院人，日均污染物濃，日均氣溫、相對濕等資，採用時間序分析的研究方法，應用Poisson 廣義相加模型分析顆污染物中粗、細顆的同健康效應。同時應用三個平的時間序研究模型（雙變反應面模型、合效應模型和分層模型）探討顆污染物和氣態污染物之間潛在的交互作用。 / 研究結果：研究發現，在校正PM₂.₅的影響后，PMc 對呼吸系統疾病導致的急性入院作用顯著，但對心腦血管疾病引起的急性入院則無明顯作用。在雙污染物（PMc 和PM₂.₅）模型中，空氣中每一個IQR（四分位間距）的PM[subscript c] 和PM₂.₅濃的增加將使每天急性呼吸系統疾病入院分別增加1.05% (95% CI: 0.19%, 1.91%)和1.81% (95% CI: 0.78%,2.87%)，使急性心腦血管疾病入院分別改變 -0.16% (95% CI: -1.07%,0.76%) 和1.86% (95% CI: 0.85%, 2.88%)。研究發現某種程6 的顆污染物和氣態污染物的交互作用。在NO₂ 或SO₂ 高水平（NO₂ 濃高於64.4μg/m³ 或 SO₂ 濃高於20.9μg/m³）的日子，PM₁₀ 對急性心臟疾病入院的影響高於NO₂ 或SO₂ 低、中水平的日子；而在臭氧高水平（O₃濃高於46.8μg/m³）的日子，PM₁₀ 對急性呼吸和循環系統疾病入院的作用低於O₃ 中、低水平的日子。 / 研究結：粗、細顆污染物對呼吸系統疾病的危害均作用顯著且相對獨，但對循環系統疾病的危害作用則主要體現於細顆污染物。同時，顆性污染物的健康危害可能被空氣中的氣態污染物水平所修飾：研究發現PM₁₀ 與NO₂ 或SO₂ 之間的協同作用，以及PM₁₀ 與O₃ 之間的拮抗作用。 / BACKGROUND: The adverse effects of particulate matter (PM) air pollution have been confirmed by many epidemiological studies. Fine and coarse particles should be considered as separate classes of pollutants and measured separately. Differentiating the effects of fine (PM₂.₅, particles with an aerodynamic diameter less than 2.5 microns) and coarse particles (PM[subscript c], particles with an aerodynamic diameter between 2.5 and 10 microns) would help in the future to support a PM[subscript c] standard. Meanwhile, ambient air pollution is a complex mixture of PM and gaseous pollutants. PM might interact with gaseous pollutants to affect the population health. / STUDY OBJECTIVES: To differentiate the effects of fine and coarse fractions of PM₁₀ and to explore the possible interaction between PM₁₀ and gaseous pollutants (nitrogen dioxide, NO₂; sulfur dioxide, SO₂; ozone, O₃) on emergency hospital admissions for cardio-respiratory diseases in Hong Kong. / METHODS: This is a time series study. Daily counts of emergency hospital admissions for cardio-respiratory diseases, daily mean air pollution concentrations and weather conditions were collected from January 1998 to December 2007 in Hong Kong. We used generalized additive Poisson model with log link allowing overdispersion and autocorrelation to examine the differential effects of PM₂.₅ and PM[subscript c]. Three parallel time series approaches (bivariate response surface model, joint effect model and parametric stratified model) were used to explore the possible interactions between PM₁₀ and gaseous pollutants. / MAIN RESULTS: The associations between PM[subscript c] and emergency hospital admissions were statistically significant for respiratory diseases but not for circulatory diseases. In two-pollutant (PM₂.₅and PM[subscript c]) model, an interquartile range increase in the 4-day moving average (lag₀₃) concentrations of PM[subscript c] and PM₂.₅ corresponded to 1.05% (95% CI: 0.19%, 1.91%) and 1.81% (95% CI: 0.76%, 2.87%) increase of respiratory admissions, respectively. The effect estimates of PM₂.₅and PM[subscript c] remained robust when adjusting for gaseous pollutants. Meanwhile, an interquartile range increase in lag₀₁ concentrations of PM[subscript c] and PM₂.₅was associated with -0.16% (95% CI: -1.07%, 0.76%) and 1.86% (95% CI: 0.85%, 2.88%) change of circulatory admissions, respectively. Some interactions between PM₁₀ and gaseous pollutants were found. The effects of PM₁₀ on circulatory hospitalizations were greatest during the days when NO₂ or SO₂ concentrations were high (the 3rd tertile, NO₂>64.4 or SO₂>20.9μg/m³). The effects of PM₁₀ on both respiratory and circulatory admissions were greatest during the days when O₃ concentrations were in low to medium levels (<=46.8μg/m³). / CONCLUSION: We found PM[subscript c] to be associated with emergency hospital admissions for respiratory diseases independent of the effect of PM₂.₅, but not for circulatory diseases in Hong Kong. The effects of PM₁₀ on cardio-respiratory hospital admissions were modified by gaseous pollutants. There were synergetic interactions between PM₁₀ and NO₂ or SO₂ on cardiac hospitalizations and antagonistic interactions between PM₁₀ and ozone on cardio-respiratory hospitalizations. These findings provide supportive evidence for a future PM[subscript c] regulation and contribute to the development of a multipollutant air quality management. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Qiu, Hong = 顆粒污染物對人群健康的短期效應 : 時間序列研究 / 邱宏. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 122-137). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Qiu, Hong = Ke li wu ran wu dui ren qun jian kang de duan qi xiao ying : shi jian xu lie yan jiu / Qiu Hong. / Abstract (English) --- p.v / Abstract (Chinese) --- p.viii / List of Contents --- p.x / List of Tables --- p.xiv / List of Figures --- p.xvi / List of Abbreviation --- p.xviii / Acknowledgements --- p.xix / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Literature Review --- p.5 / Chapter 2.1. --- Review on the differential health effects of fine and coarse particles --- p.5 / Chapter 2.1.1 --- A brief description of particulate matter air pollution --- p.5 / Chapter 2.1.2 --- The objective of this part of literature review --- p.7 / Chapter 2.1.3 --- Methods --- p.8 / Chapter 2.1.3.1 --- Inclusion and exclusion criteria of studies/papers --- p.8 / Chapter 2.1.3.2 --- Search terms and keywords --- p.9 / Chapter 2.1.3.3 --- Information abstracted --- p.9 / Chapter 2.1.4 --- Results --- p.10 / Chapter 2.1.4.1 --- Short-term effects of PM₂.₅and PM[subscript c] on mortality --- p.10 / Chapter 2.1.4.2 --- Short-term effects of PM₂.₅and PM[subscript c] on morbidity --- p.14 / Chapter 2.1.4.3 --- Biological mechanisms underlying the differential effects of PM₂.₅and PM[subscript c] --- p.18 / Chapter 2.1.5 --- Conclusion remarks --- p.19 / Chapter 2.1.5.1 --- Health effects of PM₂.₅and PM[subscript c] on mortality --- p.19 / Chapter 2.1.5.2 --- Health effects of PM₂.₅and PM[subscript c] on morbidity --- p.20 / Chapter 2.2. --- Review on the joint effects/interactions of particulate matter and gaseous pollutants --- p.21 / Chapter 2.2.1 --- Concept of Interaction --- p.21 / Chapter 2.2.2 --- The objective of this part of literature review --- p.21 / Chapter 2.2.3 --- Methods --- p.22 / Chapter 2.2.3.1 --- Search terms and key words --- p.22 / Chapter 2.2.3.2 --- Information abstract --- p.22 / Chapter 2.2.4 --- Results --- p.23 / Chapter 2.2.4.1 --- Studies on the interaction between particulate matter and gaseous pollutants --- p.23 / Chapter 2.2.4.1.1 --- Studies on the interaction between PM₁₀ and NO₂ --- p.23 / Chapter 2.2.4.1.2 --- Studies on the interaction between PM₁₀ and O₃ --- p.24 / Chapter 2.2.4.1.3 --- Studies on the interaction between PM and SO₂ --- p.26 / Chapter 2.2.4.1.4 --- Modifiers identified through multicity study --- p.30 / Chapter 2.2.4.2 --- Methodology used to detect interaction in time series studies --- p.33 / Chapter 2.2.4.2.1 --- Nonparametric bivariable response surface model --- p.33 / Chapter 2.2.4.2.2 --- Non-stratification interaction model --- p.34 / Chapter 2.2.4.2.3 --- Parametric stratified model --- p.34 / Chapter 2.2.4.2.4 --- Time series classification and regression tree (CART) model --- p.35 / Chapter 2.2.4.3 --- Biological mechanisms of interaction between pollutants --- p.36 / Chapter 2.2.5 --- Conclusion remarks --- p.38 / Chapter Chapter 3 --- Differential health effects of fine and coarse particles --- p.39 / Chapter 3.1 --- Objectives --- p.39 / Chapter 3.2 --- Materials and Methods --- p.39 / Chapter 3.2.1 --- Data on particulate pollutants and meteorology variables --- p.39 / Chapter 3.2.2 --- Data on emergency hospital admissions for cardio-respiratory diseases --- p.40 / Chapter 3.2.3 --- Statistical models --- p.42 / Chapter 3.2.3.1 --- Core model set up --- p.42 / Chapter 3.2.3.2 --- Single-pollutant and two-pollutant models --- p.44 / Chapter 3.2.3.3 --- Concentration-response relationship --- p.45 / Chapter 3.2.3.4 --- Sensitivity analysis --- p.46 / Chapter 3.3 --- Results --- p.47 / Chapter 3.3.1 --- Location of Tsuen Wan station, Tsuen Wan region --- p.47 / Chapter 3.3.2 --- Air pollution concentrations and meteorological factors --- p.47 / Chapter 3.3.3 --- Emergency hospital admissions for cardio-respiratory diseases --- p.50 / Chapter 3.3.4 --- Regression results and Sensitivity analysis --- p.51 / Chapter 3.3.4.1 --- Effects of coarse particulate matter on emergency hospital admissions for respiratory diseases --- p.51 / Chapter 3.3.4.2 --- Differential effects of fine and coarse particles on emergency hospital admissions for cardiovascular diseases --- p.56 / Chapter 3.4 --- Discussion --- p.61 / Chapter 3.4.1 --- Main findings of this study --- p.61 / Chapter 3.4.2 --- Compared with findings from the literature --- p.62 / Chapter 3.4.3 --- Exposure windows selection and possible misclassification --- p.64 / Chapter 3.4.4 --- Sensitivity analyses of main findings --- p.65 / Chapter 3.4.5 --- Biological mechanisms of the differential effects of fine and coarse particles --- p.67 / Chapter 3.4.6 --- Limitations of this study --- p.68 / Chapter 3.5 --- Conclusion and recommendations --- p.69 / Chapter Chapter 4 --- Joint effects/Interactions of PM₁₀ and gaseous pollutants --- p.70 / Chapter 4.1 --- Objectives --- p.70 / Chapter 4.2 --- Materials and Methods --- p.70 / Chapter 4.2.1 --- Data on air pollution and meteorology variables --- p.70 / Chapter 4.2.2 --- Data on emergency hospital admissions for cardio-respiratory diseases --- p.71 / Chapter 4.2.3 --- Statistical models --- p.72 / Chapter 4.2.3.1 --- Core model set up --- p.72 / Chapter 4.2.3.2 --- Three parallel time series models --- p.73 / Chapter 4.3 --- Results --- p.76 / Chapter 4.3.1 --- Air pollution concentrations and meteorological factors --- p.76 / Chapter 4.3.2 --- Emergency hospital admissions for cardio-respiratory diseases --- p.79 / Chapter 4.3.3 --- Results from single-pollutant model --- p.81 / Chapter 4.3.3.1 --- Pollution effects on emergency hospital admissions for respiratory diseases --- p.81 / Chapter 4.3.3.2 --- Pollution effects on emergency hospital admissions for circulatory diseases --- p.83 / Chapter 4.3.4 --- Joint effects/Interactions between PM₁₀ and NO₂ on cardio-respiratory hospitalizations --- p.85 / Chapter 4.3.5 --- Joint effects/Interactions between PM₁₀ and O₃ on cardio-respiratory hospitalizations --- p.91 / Chapter 4.3.6 --- Joint effects/Interactions between PM₁₀ and SO₂ on cardio-respiratory hospitalizations --- p.96 / Chapter 4.4 --- Discussion --- p.102 / Chapter 4.4.1 --- Main findings --- p.102 / Chapter 4.4.1.1 --- Effect estimates compared with previous Hong Kong studies --- p.102 / Chapter 4.4.1.2 --- Interactions between particulate matter and gaseous pollutants --- p.103 / Chapter 4.4.1.2.1 --- Interactions between PM₁₀ and NO₂ on cardiac hospitalizations --- p.103 / Chapter 4.4.1.2.2 --- Interactions between PM₁₀ and O₃ on cardio-respiratory hospitalizations --- p.109 / Chapter 4.4.1.2.3 --- Interactions between PM₁₀ and SO₂ on cardiac hospitalizations --- p.113 / Chapter 4.4.2 --- Strengths and limitations of this study --- p.116 / Chapter 4.5 --- Conclusion and recommendations --- p.119 / Chapter Chapter 5 --- Concluding remarks --- p.120 / References List --- p.122 / Chapter Appendix --- Relevant Publications and Submitted/Drafted Papers --- p.138

published_or_final_version / Community Medicine / Doctoral / Doctor of Philosophy

Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2019. / Background: A recent review on the effects of ambient air pollution on human health in sub-Saharan Africa, specifically calls for an urgent need for more epidemiological studies in developing countries due to a lack of data in these countries. Air pollution information on exposure is important for understanding and addressing its public health impact in developing countries. In many African countries, the spatial distribution of air pollutants has not been quantified even though air pollution is a global public health risk. The main goal of the study was to quantify and compare the seasonal spatial variation of household air pollution in the 4 Western Cape neighbourhoods. Methods: Weekly indoor and outdoor measurements of Particulate Matter (PM2.5), Sulphur dioxide (SO2), Ozone (O3), Carbon monoxide (CO) and Nitrogen dioxide (NO2) were conducted at 127 households in four informal settlement areas (Khayelitsha, Marconi-Beam, Masiphumulele and Oudtshoorn) during one month each in summer and winter. PM2.5 measurements were conducted using Mesa Labs GK2.05 (KTL) cyclone with the GilAir Plus Air Sampling Pump, Gases were measured using Passam passive samplers. Statistical analyses were performed using Stata V12. Simple linear regression was used to evaluate the relationship between continuous exposure levels and the respective predictor variables. These include distance to major roads, bus routes, open grills and waste burning sites. Results: The highest average weekly outdoor PM2.5 and NO2 concentrations for summer were recorded in Milnerton (8.76 µg/m3 and 16.32 µg/m3 respectively). However, the highest average concentrations during winter for PM2.5 were recorded in Oudtshoorn (PM2.5: 16.07 µg/m3), whilst the highest NO2, was recorded in Khayelitsha (NO2: 35.69 µg/m3). SO2 levels were consistently low during both seasons. Noordhoek generally recorded the lowest average levels for all pollutants. Winter average weekly concentrations were generally higher than the levels recorded in summer for all pollutants. In a sub-sample of indoor and outdoor measurements, the results were comparable for PM2.5, NO2 and CO. However, the results of Ozone (O3) showed relatively higher (~10 times) outdoor compared to indoor levels. Linear regression modelling results revealed that significant predictors of elevated exposure to PM2.5 were proximity to construction activities and open grills. Analysis demonstrated a clear dose-response relationship with distance, with open grills within 1000m associated with a 0.33 µg/m3 increase in PM2.5 to 6.77 µg/m3 at a distance of 25 meters. Results from the linear regression modelling revealed that significant predictors of exposure to NO2 were proximity to rapid transport bus stops, bus routes, taxi routes and major routes. Distance to rapid transport bus stops demonstrated an increase in NO2 between 0.09 µg/m3 (at 1km) to 2.16 µg/m3 (at 50m) during summer. A similar pattern was observed for taxi routes and bus routes displaying an increase of 6.26 μg/m3and 6.82 μg/m3 respectively within the proximity of 1000 meters. / MAUERBERGER Foundation Scholarship