Air Pollution, Social Stressors, and Neighborhood Characteristics on Childhood Asthma and Preterm Birth in California

Understanding population health involves understanding connections between social and environmental determinants of health. The life course perspective places importance on how these determinants may shape and promote pediatric health disparities. Asthma and birth outcomes are two key health outcomes of critical relevance for children’s environmental health disparities. This dissertation builds upon the growing literature on how social factors (e.g. poverty, experiences of discrimination, social deprivation) in combination with other factors (e.g. age group, atopy status, air pollution) may impact these outcomes./nData from the Study of African Americans, Asthma, Genes & Environments (SAGE II) were used for Chapters 2 and 3. In this study, African American youth with and without asthma aged 8-21 years were recruited from the San Francisco Bay Area from 2008 to 2014. Participants were part of a larger pediatric case-control study to identify genetic and socio-environmental factors in asthma prevalence and severity among minority youth in the United States. For Chapter 4, data from the California Department of Public Health’s Statistical Birth Master Files for the years 2014 and 2015 were analyzed. There were 266,127 births used in this analysis. The mother’s census tract of residence at the time of delivery was used to link person-level data to area-level data./nChapter 2 examines the independent and joint effects of racial/ethnic discrimination and early life exposure to air pollutants on asthma in the SAGE II study population. Studies on racial/ethnic discrimination, a toxic stressor, on air pollution-related asthma risk among children have been limited. This chapter evaluates the effects of racial/ethnic discrimination and high NO2/PM10 on asthma status and whether these associations vary with age. Results suggest that racial/ethnic discrimination and exposure to air pollutants, together, increase the likelihood of asthma more than either exposure alone among African American youth./nIn Chapter 3, I evaluated the association between neighborhood deprivation and asthma exacerbation among African American youth and determined if this association differs by atopy. Using principal components analysis, neighborhood deprivation scores were created for the 1,554 census tracts associated with the study participants’ residential addresses and quartiles of scores (categorized 1-4, low to high deprivation) were assigned for each participant. Generalized estimating equations were used to estimate the effects of neighborhood deprivation on asthma exacerbation. Literature relating environmental factors to asthma morbidity across different asthma phenotypes has been conflicting. Our study suggests that children, especially African American youth, with atopic asthma may be more sensitive to neighborhood-deprivation related triggers compared with those with no atopy./nIn Chapter 4, I examined the relationship between social deprivation and air pollution on preterm birth risk beyond individual level effects. Utilizing hierarchical generalized linear models, we found that the population components score (PCS), a measure of social deprivation, explained the greatest preterm birth variance and was positively associated with preterm birth after accounting for PM2.5, diesel PM, and individual-level risk factors. Furthermore, we found cross-level interactions between (1) PCS and Insurance Coverage and (2) PCS and WIC. Results from our study promote the use of cumulative measures of social deprivation versus single level measures in relation to preterm birth and highlight the interplay between key area-level and individual-level risk factors. This exploratory study supports the growing literature of a place-based understanding of preterm birth risk./nThese findings show that social factors matter for asthma and preterm birth. Exploring joint effects of social and environmental determinants is worth considering to more fully characterizing risk for these outcomes, especially for youth of color. We support the awareness and the development of policies that impact key social and environmental determinants of child health outcomes (e.g. racial/ethnic segregation, housing/neighborhood conditions, and educational/economic opportunities).

Advisor: Hammond, S Katharine