Thesis (MTech (Omgewingsgesondheid))--Cape Peninsula University of Technology, 2011. / Occupational related diseases (ORD) which result in permanent disability are compensable in South Africa. During the 2005/6 – 2007/8 financial years compensation for ORD’s totalled approximately R200 million per annum of which this study indicated, R92 milllion on average possibly related to hearing loss. This expense must surely result in negative financial consequences for both the South African government and employers. The manner in which compensation for hearing loss relating to the work place, is to be determined, was changed by Instruction 171 published in the Government Gazette dated 16 November 2001. A baseline audiogram is required for every employee who enters a noise zone during the course of employ and Instruction 171 specified that the percentage hearing loss has to be used to determine this baseline audiogram. A baseline audiogram, which is valid for the total working career of an employee, is used to monitor the hearing status of employees for purposes of possible future compensation. It consequently serves as a reference point from which hearing threshold shifts (HTS) are determined. The significance of the accuracy of this test is thus evident.Prior to the implementation of Instruction 171, various audiometric measuring tools were, in accordance with South African Standards, used in industry for purposes of hearing conservation. These measuring tools referred to above were used for various purposes which included, the determination of; compensable HL, the need for diagnostic procedures, when HL had to be reported to the Department of Labour as “an incident” and the efficiency of a hearing conservation program. With implementation of Instruction 171, these various measuring tools were reduced to a single tool namely the PLH.Naturally the accuracy of PLH determination is also important to employees as it may affect possible compensation of an individual’s hearing loss. Considering the significance of baseline audiograms for purposes of compensation, the following questions arose in this study; (i) does PLH, in its current format, measure the hearing threshold (HT) sufficiently accurately to (a) establish the baseline audiogram, (b) monitor HL for purposes of compensation, and (ii) is the PLH, as currently determined, suitable to identify further diagnostic procedures for purposes of hearing conservation?A more accurate PHL calculation procedure would be to the advantage of all parties concerned. A database which included baseline audiograms of 1101 respondents was studied to determine if the PLH, in its current format, was suitable to comply with the needs pertaining to industrial audiometry. The respondents were employees working in noise zones at various industries, located in the Western Cape and were all tested in accordance with South African audiometry standards.The current PLH determination procedure was studied and current audiometry baseline test results were reconstructed in a manner to calculate an alternative PLH. This reconstructed PLH was consequently used to determine a new B-baseline audiogram. StatSoft Statistica, software was used to statistically compare the current baseline audiogram with the B-baseline audiogram. The study revealed that the B-baseline audiogram succeeded to on average produce a 17% improvement (more accurate) in the determination of the PLH. The PLH of the B-baseline audiogram can thus be regarded as more representative of the true HT of employees.Based on the results of this study it is recommended that the current determination of the PLH used to establish the baseline, be amended. The proposed amendment (B-baseline audiogram) still uses the HT of the two tests done in accordance with Instruction 171 and no amendment of the test procedure is thus required. As the PLH of the baseline and the diagnostic baseline audiogram is currently used for compensation purposes, it is recommended that the B-baseline method be used for both the baseline and diagnostic baseline audiograms.

Thesis (MTech (Environmental Health))--Peninsula Technikon, Cape Town, 2004 / AIM &; OBJECTIVES: a) To quantify human vibration exposnres among the various similar occupational groups present on the mine, b) To determine the degree of vibration risk posed onto the mineworkers and c) To recommend and implement a sustainable human vibration management control progranune. METHODOLOGY: A cross-sectional descriptive study design was carried out on 135 mine workers employed in various similar occupational groups at Rossing Uranium mine, Namibia Data acquisition originated from a multi-stage proportionally stratified random sampling technique. An approved Human Vibration measuring instrument was utilized to measure Hand-arm and Wholebcdy vibration exposure levels [Aeq (m/s2 )] prevalent among the similar exposure groups. A structured questionnaire, developed specifically for the actual work environment enabled the collection of information such as work history, type of vibration exposure, exposure duration and vibration symptoms. Furthermore, group specific results [A(8)] were computed by means of the latest internationally accepted Health & Safety Executive Vibration calculators. In addition, statistical analyses were performed in order to establish the occupational groups that are at increased risk for the development of hand-arm and wholebody vibration induced health disorders.

Thesis (MTech (Consumer Science: Food and Nutrition))--Cape Peninsula University of Technology, 2016. / Background: The different types and forms of rooibos and the ways in which it is prepared and flavoured for consumption influences its total polyphenol content and total antioxidant capacity (TAC) and hence depends on its consumer practices. Design: Phase 1 of the study entailed the selection and preparation of different rooibos types and forms; rooibos brewed for different times; and with different household and commercially added flavourings to determine the total polyphenol content, TAC, flavonol and flavanol content; and subsequent identification of the optimal cup of rooibos based on the first two biochemical parameters. For Phase 2 a questionnaire was used to obtain information on the profile of the adult rooibos herbal tea consumer, as well as of those consuming the optimal cup of rooibos. Results: The following prepared rooibos samples delivered the higher biochemical parameter content: green / unfermented (type representative); green / unfermented leaves and powdered extract (form representatives); that brewed for 10 minutes or longer; and those with added honey. The optimal cup of rooibos was identified as the one brewed for 10 minutes or longer. The older respondents and those with a lower level of education consumed a higher daily amount of rooibos (p < 0.05) and those who brewed rooibos in a teapot consumed the optimal cup (p < 0.05). However, very few respondents consumed the advised number of cups per day (< 1%) and the identified optimal cup (15.9%). Conclusions: Rooibos consumers in this study did not consume it in sufficient amounts and did not brew it for long enough to fully gain from its attributed health benefits.

Ma Ka Ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 99-118). / Abstracts in English and Chinese. / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- What are prebiotics? --- p.1 / Chapter 1.2 --- Current prebiotics and their development --- p.2-3 / Chapter 1.3 --- The intestinal microflora --- p.3-4 / Chapter 1.3.1 --- Bacteroides --- p.5 / Chapter 1.3.2 --- Bifidobacteria --- p.5 / Chapter 1.3.3 --- Clostridia --- p.5-6 / Chapter 1.3.4 --- Lactobacilli --- p.6 / Chapter 1.4 --- Bacterial colonic fermentation --- p.7-8 / Chapter 1.4.1 --- Carbohydrates metabolism in colonic bacteria --- p.8-10 / Chapter 1.4.1.1 --- Carbohydrates metabolism in Bacteroides --- p.11 / Chapter 1.4.1.2 --- Carbohydrates metabolism in Bifidobacteria --- p.11 / Chapter 1.4.1.3 --- Carbohydrates metabolism in Clostridia --- p.11 / Chapter 1.4.1.4 --- Carbohydrates metabolism in Lactobacilli --- p.12 / Chapter 1.5 --- Health benefits of prebiotics --- p.12-13 / Chapter 1.6 --- Metabolites of fermentation: Short-chain fatty acids (SCFAs) --- p.14-15 / Chapter 1.7 --- Applications of prebiotics as functional food ingredients --- p.16 / Chapter 1.8 --- Methodology for evaluating prebiotics --- p.17 / Chapter 1.8.1 --- In vivo fermentation study --- p.17 / Chapter 1.8.2 --- Human clinical study --- p.17-18 / Chapter 1.8.3 --- In vitro fermentation study --- p.18-19 / Chapter 1.9 --- Methods of bacterial enumeration --- p.19-20 / Chapter 1.9.1 --- Fluorescent in situ hybridisation --- p.20-22 / Chapter 1.9.2 --- Bacterial enumeration by automatic image analysis --- p.22-23 / Chapter 1.10 --- Sugar alcohols --- p.23 / Chapter 1.10.1 --- Sugar alcohols and their functions --- p.23-25 / Chapter 1.10.2 --- Digestion and absorption of sugar alcohols --- p.25-26 / Chapter 1.10.3 --- Metabolism of sugar alcohols in humans --- p.26 / Chapter 1.10.4 --- Adverse effect of sugar alcohols --- p.26-27 / Chapter 1.11 --- Fermentation of sugar alcohols in colonic bacteria --- p.27 / Chapter 1.12 --- Project objectives --- p.28 / Chapter Chapter 2. --- Materials and Methods --- p.29 / Chapter 2.1 --- Materials --- p.29 / Chapter 2.2 --- Static batch culture fermentation --- p.29 / Chapter 2.2.1 --- Substrate preparation --- p.29-30 / Chapter 2.2.2 --- Human fecal inoculum preparation --- p.30-31 / Chapter 2.3 --- Dry matter and organic matter disappearance in batch fermentation --- p.31 / Chapter 2.4 --- Determination of flow rate in the continuous fermentation system. --- p.32-33 / Chapter 2.5 --- Three-stage continuous fermentation culture system --- p.34 / Chapter 2.5.1 --- Initial set-up --- p.34-35 / Chapter 2.5.2 --- Continuous fermentation --- p.35-36 / Chapter 2.6 --- Validation of fluorescent in situ hybridisation (FISH) method --- p.36 / Chapter 2.6.1 --- Oligonucleotide probes for FISH --- p.36-37 / Chapter 2.6.2 --- Cultivation of pure human intestinal bacterial culture --- p.37-38 / Chapter 2.6.3 --- Validation of oligonucleotide probes for FISH --- p.38-40 / Chapter 2.7 --- Bacterial enumeration of fermentation broth by FISH --- p.41 / Chapter 2.7.1 --- Automated image analysis --- p.41-42 / Chapter 2.7.2 --- Quantification of bacteria --- p.43 / Chapter 2.8 --- Gas chromatographic determination of short-chain fatty acids (SCFAs) --- p.44-46 / Chapter 2.9 --- Statistical analysis --- p.46 / Chapter Chapter 3: --- Results and Discussion --- p.47 / Chapter 3.1 --- Dry matter and organic matter disappearance in batch fermentations --- p.47-48 / Chapter 3.2 --- Validation of genus-specific oligonucleotide probes for FISH by pure bacterial culture --- p.48-50 / Chapter 3.3 --- FISH and multi-color FISH of human fecal bacteria --- p.50-53 / Chapter 3.4 --- Enumeration of fecal bacteria with the CellC software --- p.53-54 / Chapter 3.5 --- Colonic bacterial profile in batch culture in vitro fermentation --- p.55 / Chapter 3.5.1 --- Total colonic bacteria --- p.55-56 / Chapter 3.5.2 --- Bacteroides --- p.57-59 / Chapter 3.5.3 --- Bifidobacteria --- p.60-62 / Chapter 3.5.4 --- Clostridia --- p.63-64 / Chapter 3.5.5 --- Lactobacilli --- p.65-66 / Chapter 3.6 --- Short-chain fatty acids (SCFAs) in batch in vitro fermentation --- p.67 / Chapter 3.6.1 --- Total SCFAconcentration --- p.67-68 / Chapter 3.6.2 --- Acetate --- p.68 / Chapter 3.6.3 --- Propionate --- p.69 / Chapter 3.6.4 --- Butyrate --- p.69-70 / Chapter 3.7 --- Determination of flow rate in three-stage continuous fermentation system --- p.71-73 / Chapter 3.8 --- Colonic bacterial profile in three-stage continuous fermentation system --- p.74 / Chapter 3.8.1 --- Total colonic bacteria --- p.74-75 / Chapter 3.8.2 --- Bacteroides --- p.76 / Chapter 3.8.3 --- Bifidobacteria --- p.77-78 / Chapter 3.8.4 --- Clostridia --- p.79-80 / Chapter 3.8.5 --- Lactobacilli --- p.81 / Chapter 3.9 --- SCFAs in three-stage continuous fermentation system --- p.82 / Chapter 3.9.1 --- Total SCFA concentration --- p.82-87 / Chapter 3.9.2 --- SCFA molar ratio --- p.88-89 / Chapter 3.9.3 --- Acetate --- p.90-91 / Chapter 3.9.4 --- Propionate --- p.92-93 / Chapter 3.9.5 --- Butyrate --- p.94-95 / Chapter Chapter. 4 --- Conclusions and Future Works --- p.96-98 / List of References --- p.99-117 / Related Publications --- p.118

Individuals who experience homelessness are exposed to stressors that have the potential to precipitate mental and physical health complications that can present serious threats to multiple areas of these individuals' lives. Although the path to becoming and remaining homeless is different for every individual, there may be some commonality specific to homelessness that makes certain individuals who experience homelessness more vulnerable than other individuals to the expression and potentially devastating course of psychopathology. Guided by the diathesis-stress model, the intent of this study is to explore the question, following a first hospitalization for mental illness ("schizophrenia spectrum disorder" or "other diagnosis"), what are the associations of homelessness with psychiatric symptom severity and how do risk factors of family history of mental illness, low intelligence, housing independence, hopelessness, and lack of social support interact with homelessness? To answer this question, a secondary analysis was performed on data from the Suffolk County Mental Health Project, a longitudinal study that sought to investigate the course of schizophrenia in an epidemiologic sample of first-admission patients. A sub-sample of 548 cases taken from the parent study were further subdivided into two cohorts; individuals diagnosed with schizophrenia spectrum disorder and those diagnosed with non-schizophrenia mental illness. A multilevel analysis was conducted for four different outcome variables, measuring psychotic, disorganized, and depressive symptoms as well as global functioning, in order to determine whether or not there is a significant association between homelessness and the severity of psychiatric symptomatology. Through the continued use of multilevel analytic models and interaction plots, significant confounding variables were examined to determine whether or not they facilitated interactions with homelessness. Homelessness was found to produce a small, but significant effect, for both cohorts across all four outcome variables. Additionally, applied to different outcome variables, the five confounding variables were also found to have small-to-medium-sized, significant interactions with homelessness. The results of this study provide additional statistical support to other studies looking at similar populations.

This dissertation examines topics related to development, environment and health in developing countries using empirical methods. In the first chapter, I study how developing countries can increase enforcement to reduce subsidy leakage in public programs, by investing in the state capacity to target program beneficiaries. This chapter further attempts to understand how the formal sector and black market respond to a policy that reduces diversion of a subsidized commodity. I explore these questions using the case of a Unique ID-based direct fuel subsidy transfer policy in India. Second chapter focuses on the health and wealth trade off near mineral mining operations in developing countries. Using extensive data on mining, health outcomes and assets from 44 developing countries, this study quantifies the wealth gain and adverse health impact of mineral mining. With a number of empirical strategies, this study shows that, despite high wealth gains, how heavy metal mining significantly increases the level of anemia in women and stunting in children living near mines. In the third chapter, I estimate demand for a water quality diagnostic product -- arsenic testing, when it is offered at a price. I further look into various aspects related to selection, learning and households behavioral response to the information. This study is based on a field experiment in Bihar, India.

The broad aim of this dissertation is to understand the early impact of HPV vaccination in females at the population level. Three important public health questions are addressed: 1) Is HPV vaccination doing what is expected: decreasing the prevalence of vaccine-type HPV 6, 11, 16 and 18 which are etiologically linked to invasive cervical cancer and genital warts?; 2) Is there evidence of beneficial cross-protection (decreased prevalence) of any of the other non-vaccine-targeted high-risk (HR) HPV genotypes?; and 3) With the expected decline of HPV 16 and 18, are there deleterious virological consequences, such as type-replacement (increased prevalence) with a rise of non-vaccine-targeted HR HPV? In the first chapter, I assess and synthesize peer-reviewed literature published from 2007 to 2013 that documented early impact of HPV vaccination. Seventeen ecological studies were stratified into three tiers based on degree of vaccination impact (cervical abnormalities, genital warts, and HPV DNA) and incidence or prevalence in samples from a pre-HPV vaccination time period (pre-2007) with that of a post-vaccination time period (post-2007) were compared. In the second chapter, I investigate vaccine-type HPV prevalence changes between pre- and post-vaccine periods in over 8,000 females aged 14-59 years enrolled in the NHANES HPV Vaginal Swab Surveys from 2003-2010. In the third chapter, I test for evidence of non-vaccine-targeted HR HPV genotypic cross-protection and type-replacement in NHANES Survey females from the pre- and post-vaccine periods. Finally, I conclude the dissertation with a summary of the findings and a discussion of the public health impltcations and offer suggestions for future research.

The etiology of obesity is heterogeneous as are the cardio-metabolic complications, associated with it. The cardio-metabolic profile of obese individuals places them at risk of a range of chronic metabolic diseases including diabetes. Paradoxically, a subset of the population classified as obese based on established methods present with few metabolic abnormalities, whereas a subset classified as non-obese present with a wide range of abnormalities. The observed heterogeneity suggests not only that excess adiposity is likely one of many determinant of metabolic complications, but also that our methods of measuring obesity might not be fully capturing the underlying biological mechanisms at play. The heterogeneity by which obesity presents itself in the general population is becoming more pertinent to the field of infectious diseases as findings increasingly implicate obesity in impaired host defenses and increased susceptibility to a range of different infectious organisms, one of which is Staphylococcus aureus. S. aureus is an opportunistic pathogen with significant infectious burdens in clinical, community as well as incarcerated settings. The organism also asymptomatically colonizes human mucosal surfaces, particularly the anterior nares. The anterior nares of approximately 25-30% of US adults are colonized at any given time, and prior colonization serves as a strong predictor of subsequent infection. Obese females have been consistently shown to be at elevated risk of S. aureus colonization, however, findings amongst obese males have been inconsistent. The mechanism by which obesity increases risk of colonization remain unclear, however, many cite the underlying metabolic dysfunction that frequently accompanies obesity. Given the global burden of obesity and increasing evidence that it impairs host defenses, understanding how obesity increases host colonization with S. aureus is imperative. The overall objective of this dissertation was therefore to evaluate the influence of obesity and metabolic abnormalities on S. aureus colonization among New York State Maximum-Security prison inmates. The objective of the dissertation was met using three aims. First a systematic review was conducted to assess the different definitions used to define persistent S. aureus colonization in community dwelling adults, as well as the reported prevalence estimates associated with those definitions. The study demonstrated that a considerable amount of variation existed in the way persistent colonization was defined in the extant literature. Despite the variation however, the prevalence of persistent S. aureus carriage remained relatively consistent after categorizing the different definitions into four general groups. The review also demonstrated that two groups of persistent carriers might exist. Therefore, differentiating strain persistence carriers from species persistence carriers may reconcile some of the inconsistencies with regard to length of strain carriage reported in the literature. Second, the influence of metabolic heath (a measure incorporating both body mass index (BMI) and metabolic abnormalities) was assessed. A significantly higher probability of S. aureus colonization of the anterior nares and/or oropharynx was observed among metabolically abnormal normal weight (BMI < 25 kg/m²) as well metabolically abnormal obese (BMI ≥ 30 kg/m²) females when compared to metabolically healthy females. No significant association was observed between the categories of metabolic health and the prevalence of S. aureus colonization among males. We did, however observe a significant decline in exclusive oropharyngeal colonization among obese male inmates with metabolic abnormalities. Lastly, factors associated with persistent S. aureus carriage were evaluated in the third aim. Approximately 27% of the population was persistent carriers at the species level and 17% were persistent carriers at the strain level. Obesity was independently associated with species persistent carriage but not strain persistent carriage. Correspondence analysis evaluating strain compositional differences between exclusive persistent anterior nares carriers, exclusive persistent oropharynx carriers, exclusive persistent carriers at both the anterior nares and oropharynx and intermittent carriers suggested compositional differences existed between the different groups. More specifically, the relative abundance of certain S. aureus strains appeared more prominent among exclusive nasal carriers as compared to all other carriage/mucosal site types (exclusive oropharynx, both nasal and oropharynx.

Background: Maternal sensitivity, or high quality maternal caregiving, in which the mother leads and structures the infant’s early experiences in a responsive way, is associated with improved child development outcomes and health, both in the immediate and long term, and thus an important area of public health research. Although previous research has established that exposure to high maternal sensitivity advances the outcome of infant cognitive development, factors such as breastfeeding, which is hypothesized to confound the association, or depression, which is negatively associated with sensitivity, have not yet been examined together in a single study. Maternal alcohol use, associated with both breastfeeding and depression, has not been examined in any study investigating the sensitivity-cognitive development association. The majority of infant studies examining the maternal sensitivity-infant cognition association include either normal birth weight infants or LBW infant samples. Using the LBW category may result in potential misclassification since this group combines at least two different phenomena and includes infants who have had either compromised gestational time as in the case of small for gestational age (SGA), or insufficient gestational time, as in the case of premature birth, or both. In studies using comparison groups, normal birth weight infants are sometimes compared to LBW infants or infants born prematurely. However, none of these studies examine the association between sensitivity and cognitive outcome in infants exclusively premature or SGA. Aim: This study investigates the association of several factors: (1) maternal depressive symptomology, (2) breastfeeding, (3) concurrent maternal alcohol intake and (4) infant biological vulnerability upon outcomes of (1) Maternal Sensitivity and (2) Infant Cognitive Development, as well as their effect on the association between senstivity and cognitive development. Methods: Using data from the Early Childhood Longitudinal Study-Birth (ECLS-B) Cohort, a nationally representative sample of U.S. born children, depressive symptomology was evaluated as an effect-modifier, and breastfeeding was evaluated as a confounder of the sensitivity-cognitive development association. Maternal alcohol use and biological vulnerability were also hypothesized to be confounders of the sensitivity-cognitive association. Univariate and multi-variable regression analyses were used to examine whether the four maternal factors were associated with Maternal Sensitivity, measured by the Nursing Child Assessment Teaching Scale (NCATS), and with Cognitive Development, measured by the Bayley Scale of Infant Development, Research Edition (BSF-R). Results: In univariate analyses, breastfeeding, depressive symptomology and alcohol use were associated with maternal sensitivity but only breastfeeding and depressive symptomology were associated with Cognitive Development In a final model examining the effect of sensitivity, depressive symptomology and breastfeeding upon the outcome of Cognitive Development, sensitivity (β =.375, p<.001) remained significantly associated with cognitive development after adjusting for breastfeeding (β =1.592, p<.001), depressive symptomology (β =-.061), p<.05), demographic factors and birthweight (R2=.053, p<.001). Depressive symptomology was not an effect modifier of the sensitivity-cognitive developmental association. Univariate regression analyses showed that of the measures of biological vulnerability, premature birth had the greatest association with both sensitivity and cognitive development in comparison to the LBW or SGA. In a multivariate regression model in which maternal sensitivity as an outcome, premature birth (β= -.524***) was associated with maternal sensitivity (R2=.100, p<.001), after adjusting for maternal depression and breastfeeding. In a multivariate regression model analysing the effect premature birth and maternal factors, including sensitivity in which cognitive development was the outcome, maternal sensitivity (β=.369, p<.001) and breastfeeding (β=1.567, p<.001) were positively associated with infant cognitive development, while premature birth (β= -2.949, p<.001) was negatively associated (R2=.049, p<.001). Conclusion: This research demonstrates that an independent association between maternal sensitivity and infant cognitive development remains even after adjusting for breastfeeding, and that breastfeeding is a separate means to advancing infant cognitive development. Premature birth, rather than SGA drove the negative association between low birth weight and cognitive development. Future research should look at the effects of premature birth separately from SGA when examining developmental outcomes. Keywords: Maternal Sensitivity, Parenting, Cognitive Development, Breastfeeding, Maternal Depression, Premature Birth, Small for Gestational Age, Low Birth Weight

Age-related cognitive decline is a growing public health issue as increases in life expectancy are expected to substantially raise the prevalence of cognitive impairment and dementia. An estimated 46.8 million individuals are currently living with dementia, with the global prevalence expected to double every 20 years. Emerging evidence suggests that ambient air pollution from traffic and other sources may be an important risk factor for cognitive decline in addition to its association with other cardiovascular and neurological outcomes. The aim of this dissertation was to first investigate the association between long-term exposure to ambient air pollution and cognitive decline among older adults in an urban population within Northern Manhattan. I then set out to assess specific mechanisms involved in the association between long-term exposure to ambient air pollution and cognitive decline, specifically investigating the ApoE4 allele, age, and current smoking behavior as effect modifiers of the association between long-term exposure to ambient air pollution and cognitive decline. I found evidence of an adverse effect of ambient air pollution on the cognitive functioning of older adults. Overall, exposure to higher levels of ambient air pollution was highly predictive of lower cognitive scores, but at baseline only. Contrary to the current hypothesis, limited evidence was found for an association between estimates of air pollution and trajectories of cognitive decline. The patterns of effect were similar across pollutant types and cognitive domains in this aging, urban population. I found strong evidence of effect modification by smoking status, where contrary to the hypothesis; the overall effects of ambient air pollution on cognition and cognitive decline were stronger among individuals who never smoked. The impact of effect modification by age category was most prominent in the memory and language cognitive domains. Among individuals less than 75 years old at baseline, there was a stronger association between a one IQR increase in air pollutants and cognitive domain scores at baseline as compared to individuals 75 years and older. I did not observe conclusive evidence of an association between air pollution and cognition in models stratified by APOE-4 status. To my knowledge, this is the largest study to analyze the association of ambient air pollution on cognition and cognitive decline over time in a racially and ethnically diverse sample. These results further support the current evidence on the role of air pollution on accelerated cognitive aging and brain health.