<p> Respiratory health is closely linked to air quality. Globally, poor indoor and outdoor air quality create immense public health burden of disease and disability that is most evident in rural regions of low and middle income nations. To date, Southeast Asia (SEA) boasts a number of emerging economies; however, rapid economic growth comes at a cost, and environmental pollution, especially air pollution, and tobacco use remain obvious threats to health. In rural SEA, a paucity of health data adds to the present problem that includes community level risk factors that include indoor cooking fire smoke, domestic dust-dirt exposure, and agricultural animal handling. Individual risk factors for respiratory disease such as an unstudied form of tobacco use known as "bamboo water pipe smoking" is prevalent in rural SEA and considered socially acceptable (Centers for Disease Control &amp; World Health Organization, 2010); however, the exposure to carbon monoxide and health risks from its use remains unknown. This form of water-filtered tobacco use may produce byproducts of combustion that might affect respiratory health and lung function, and if it does, is without evidence. Prior studies of water-filtered smoking include the Eastern Mediterranean tobacco water pipe (i.e. hookah) and indicate that high levels of carbon monoxide inhaled by the smoker. Notably, myths or beliefs attributed to the safety of a tobacco water-bath filtered smoke have been unsupported. </p><p> In the presented dissertation, I continue the assessment of water-filtered tobacco smoke and present two studies that include the first in-field investigation of bamboo water- pipe use, carbon monoxide exposure, and lung function using a sample of rural adult males from Laos PDR. In my first study, I examine carbon monoxide exposure in bamboo water pipe smokers in assessing water-filtered tobacco smoke. In my second study, I report findings from the first lung function (spirometry) assessment of bamboo water pipe smokers of rural Laos PDR. Findings of both my studies indicate that 1) water-filtered bamboo water pipe smoking does not remove carbon monoxide prior to inhalation; 2) bamboo water pipe use produces compatible carbon monoxide to cigarette use; 3) bamboo water pipe use may harm lung function; and 4) community level risk factors in rural areas of Southeast Asia (i.e. cooking fire smoke) may be harmful to health. Further studies are warranted to evaluate the health effects from bamboo water pipe use and community level risk factors in rural areas of Southeast Asia.</p>

<p> The adverse effects of air pollution on human life is of serious concern for today&rsquo;s society. Two population groups that are especially vulnerable to air pollution are pregnant women and their growing fetuses, and the focus of this thesis is to study the effects of air pollution on these populations. In order to address the methodological limitations in prior research, we quantify the impact of air pollution on various adverse pregnancy outcomes, utilizing machine learning and novel causal inference methods. Specifically, we utilize two semi-parametric, double robust, asymptotically efficient substitution estimators to estimate the causal attributable risk of various pregnancy outcomes of interest. Model fitting via machine learning algorithms helps to avoid reliance on misspecified parametric models and thereby improve both the robustness and precision of our estimates, ensuring meaningful statistical inference. Under assumptions, the causal attributable risk that we estimate translates to the absolute change in adverse pregnancy outcome risk that would be observed under a hypothetical intervention to change pollution levels, relative to currently observed levels. The estimated causal attributable risk provides a quantitative estimate of a quantity with more immediate public health and policy relevance.</p><p>