A growing literature in public health has suggested that the local food environment influences food choice and obesity outcomes. This dissertation recognizes the importance of the food environment as a potential determinant of health behaviors and health outcomes. These studies examine how the farmers' markets and the workplace food environment impact dietary behaviors and obesity.

Chapter 2 examines the associations between the presence of a farmers' market near home and dietary behaviors among adults in California. It also aims to address whether the selection effect is influencing the relationship between farmers' markets and dietary behaviors. Using data from the 2005, 2007, and 2009 California Health Interview Survey and the locations of Certified Farmers' Markets, this study tested the association of farmers' markets near home with obesity and dietary behaviors, using (1) a directed acyclic graphical causal approach, and (2) a cross-year variation in farmers' markets to control for selection. Results suggest that, adjusting for demographic characteristics, survey year, and the presence of farmers' market during both the current survey year and other survey years, adults living near a farmers' market are less likely to be obese and more likely to eat three or more servings of fruits and vegetables per day. Living near a farmers' market was not significantly associated with soda consumption. This study suggests that locating new farmers' markets in areas with low demand for fruits and vegetables would increase healthy dietary habits.

Chapter 3 tests the associations between farmers' markets near home and fruit and vegetable consumption among adults in California. It also aims to address whether farmers' markets influence fruit and vegetable consumption through the mechanism of increasing perceptions of availability of fresh produce. Using data from the 2011-2012 California Health Interview Survey and the locations of Certified Farmers' Markets, this study examines the impact of farmers' markets on a population level by testing the relationship between farmers' markets upon fruit and vegetable consumption, via perceived availability of fruits and vegetables. Four sets of logistic regressions were conducted to examine this relationship. Farmers' markets were positively associated with perceived availability of fresh produce. Both perceived availability of fresh produce and presence of a farmers' market were independently associated with increased fruit and vegetable consumption. However, when both variables were included in the model, the magnitudes of the associations were very similar. This similarity reflects the weak association between farmers' markets and perceived availability in the sample. The weak association between farmers' markets and perceived availability suggests that the principal pathway for the impact of farmers' markets on consumption is not through increasing perceptions of availability but something else. Regardless, farmers' markets are a useful strategy in promoting consumption of fruits and vegetables.

Chapter 4 studies an area of the food environment relatively unexplored by researchers--the workplace food environment. Using data from Wave 2 of the Los Angeles Family and Neighborhood Survey (LAFANS), a longitudinal, population-based survey of individuals living in Los Angeles County and 2007 Los Angeles County Department of Public Health food outlet data, this study examines the association of the food environment around the workplace with obesity and dietary behaviors among adults. Results suggest that, adjusting for demographic characteristics, the workplace food environment is associated with obesity. There were no significant associations between the workplace food environment and dietary behaviors. The relationship between the workplace food environment and obesity appears to taper off as the food environment becomes saturated with unhealthy food outlets. Further research is needed to understand the relationship between the workplace food environment and obesity and dietary behaviors.

Although asthma occurs among Californians at all socio-economic levels, it disproportionately affects low-income Californians, who miss more days of work and school, are more likely to have frequent asthma symptoms, and are more likely to go to the emergency department or be hospitalized for asthma care. In this report, the burden of asthma on low-income Californians is examined by geography, race/ethnicity, age and access to care, among other factors. The authors suggest that disparities in asthma prevalence and care are likely due to a number of factors including inadequate access to health insurance coverage, lack of continuity and quality of health care, and an increased likelihood of exposure to asthma triggers and they point to policy and environmental changes that will likely help address these disparities, including adequate health care coverage, quality health care for low-income Californians with asthma, and asthma-friendly environments.

SUMMARY: In California, more than 2 million adolescents (58%) drink soda or other sugar-sweetened beverages every day, and more than 1.6 million adolescents (46%) eat fast food at least twice a week. Adolescents who live and go to school in areas with more fast food restaurants and convenience stores than healthier food outlets such as grocery stores are more likely to consume soda and fast food than teens who live and go to school in areas with healthier food environments. State and local policy efforts to improve the retail food environment may be effective in improving adolescents’ dietary behaviors.

In California, more than 1.3 million adolescents (38%) do not participate in physical education (PE) at school, and this rate increases dramatically with age, from just 5% at age 12 to 77% at age 17. In addition, only 19% of teens meet current physical activity recommendations. Participation in PE at schoolis associated with more overall physical activity. Policies that promote more opportunities for physical activity, including those that help schools meet or exceed current PE requirements, can contribute to greater levels of physical activity for adolescents.

The prevalence of both diabetes and obesity has grown significantly in California. Six million adults are obese and an additional 9.3 million are overweight. Obesity is a significant risk factor for diabetes; more than two million adults have been diagnosed with diabetes in California. Obesity and diabetes disproportionately affect people of color, the poor and those with the least education in California. Policy and environmental changes that promote and encourage physical activity and healthy eating will likely prove most effective in combating obesity and related conditions.