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ABSTRACT Background: Asthma is a chronic lung disease that inflames and narrows the airways. This results in recurrent episodes of coughing, wheezing, shortness of breath, and chest tightness. Although the causes of asthma are poorly understood, genetic and environmental factors have been implicated in the development and exacerbation of the disease. Among environmental risk factors, cigarette smoke is a well-known risk factor to trigger asthma symptoms. Exposure to secondhand smoke irritates the airways and may trigger an attack in adults with asthma. Smoke-free laws and regulations in the United States differ by state. The enforcement of smoke-free legislation has been related to asthma rates as it has been shown that they lead to a sustained drop in emergency hospital admission for asthma among adults. These laws and regulations are also necessary in reducing smoking rate and secondhand smoke exposure. Objective: The purpose of this thesis is to examine the association between tobacco smoke rates and asthma status among adults at the national and state levels and to evaluate the effects of state smoke-free laws and regulations on tobacco smoking rate among adults with asthma. Methods: The Centers for Disease Control and Prevention’s 2009–2010 Behavioral Risk Factor Surveillance System data was used for the analyses. SAS-callable SUDAAN (version 10.0.0, RTI International, NC) was utilized to account for the complex sampling design of the BRFSS, and sample weights were used to produce estimates that were generalizable to the state and U.S. adult population. In addition to calculating descriptive statistics, chi-square tests and multivariate logistic regression were used to test for group differences and association between variables of interest. State level smoking rates were ranked to identify states that are in the lower and upper 20th percentiles and compare them with states’ smoke-free laws and regulation status. Results were considered significantly different if 95% confidence intervals (CIs) did not overlap or if statistical testing at p<0.05 was applicable. Results: Asthma prevalence rates are higher among adults that smoke cigarettes (10.5%, [aPR] =1.2) compared to non-smokers (7.8%, [aPR] =1.0). Of the 869,519 adult respondents in the survey, 8.5% reported having asthma. Nearly one-fifth (17.2%) of adults without asthma smoked cigarettes, while (21.7 %) of adults with asthma smoked. Females (10.5%) had higher asthma prevalence rates than males (6.4%). Black persons (10.0%), persons of American Indian (13.0%) descent had higher, and those of Hispanic (6.7%) descent had lower asthma rates than white persons (8.6%). Adults with a high school education or less (9.1%) had higher asthma rates than those with an education level that was equivalent to a 4 year college or more (7.3%) , and those with low income (<$15,000) had higher rates (13.3%) than those with high income (6.8%). Percentage of male (23.4%) and females (20.7%) with asthma who smoke are higher than those that do not smoke (19.3% and 15.1%, respectively). Asthma prevalence rates and smoking rates vary by geographic location. Smoking rates among adults with asthma was highest in the South (LA, AL, SC, TN, OK, MS, AR, WV, KY) and a couple of Midwest states (OH, IN,). Evaluating the association between the 2008 State of Tobacco Control Report and smoking rate among adults with asthma by state showed a statistically significant relationship between smoking rate among adults with asthma and smoke-free policy and regulation at the state and national level. On average, states with the lowest smoking rate among persons with asthma (smoking rates less than 20th percentile) had significantly higher smoke-free policy grades (mean grade [sd]=7.2 [1.99]) than states with a high smoking rate (smoking rate of 80th percentile or more) (mean grade [sd]=2.0 [2.00]) (p-value < 0.00001). Conclusion: Although most U.S. state smoke-free policies and regulations are relatively new, it is evident that these laws are effective in promoting cessation among adults and reducing nonsmokers’ exposure to secondhand smoke. The study found that smoke-free laws may improve health by lowering asthma prevalence and smoking rates among adult smokers. Also, these policies in turn protect non-smokers from the harmful health effects of secondhand smoke.

Asthma has been reported in children as a leading chronic illness in the US and around the world. It is also the third leading cause of hospitalization among children under the age of 15, and is also one of the most common causes of school absenteeism. Children are at higher risk of asthma attacks and they pose a higher burden on health care system. Nearly 20.6% of middle and high school children in Florida have been told they have asthma, this prevalence has grown over 3% from 2006 to 2012. Changes in air pollutant levels are often related to health outcomes, e.g. prevalence of chronic asthma. Exposure to ambient air pollutants have been reported to exacerbate asthma attacks especially in children. Often agencies and governing bodies utilize national level health impact assessments (HIAs) to estimate local levels of health impacts. The US EPA (Environmental Protection Agency) developed the Benefit Mapping and Analysis Program (BenMAP) to estimate impacts on health due to changes in air pollution. Recent studies have shown that assessment of regional exposure is important to understand health impacts of pollutants at the local level. To use BenMAP effectively for HIA in Florida, one may have to update the prevalence rates and concentration response (CR) functions in BenMAP with Florida data. The main purpose of the research was to develop a method which can estimate impact of change in criteria pollutants on childhood asthma outcomes in Florida. The rates present in BenMAP are based on national estimates, which are higher than the rates for Florida. If these rates are used for the HIA method then the change in asthma emergency department visits estimated by BenMAP may be an overestimate with higher uncertainties. There are no baseline rates for asthma exacerbation ED visits in BenMAP, an asthma exacerbation is a more severe and poorly managed case of asthma. Asthma ED visit prevalence rates will tend to overestimate the asthma exacerbation rates by 64%, if used. Detailed review of US-EPA’s BenMAP software and peer reviewed literature was performed to identify the gaps in BenMAP for asthma assessments. The CR functions were developed using local pollutant and outcomes data. CR functions were added to BenMAP to bridge the gaps. The baseline prevalence and exacerbation rates at county level by age group, gender and race ethnicity were developed. This study highlights that an increase of 10 µg/m3 of PM2.5 contributes about 2% to asthma ED visit rate, in children 5-12 and is lower, for 13-18 olds (0.6%). The baseline prevalence and exacerbation rates at county level for asthma in children differed by race/ethnicity. This study publishes the ED rates by county and by gender, race and ethnicity from 2010 to 2014, which are recent rates and have not been published to such granularity by the State or by any other researcher. Current pollutant data in BenMAP is only available through 2008, and EPA has recommended it should be updated for analysis purposes. This study has updated the monitor data in BenMAP for Florida counties for 2010-2014. There are three major contributions of this study. Firstly, the study contributes to publishing childhood emergency department prevalence rates for asthma and exacerbation in the State of Florida by age group, race/ethnicity and gender. Secondly, development of concentration response functions specific to Florida using the time series analysis to show the impact of PM2.5 on asthma exacerbation emergency department visits, incorporating both temporal and spatial variability of PM2.5 during the study period. Finally, the study demonstrates the utility of using local (county-level) baseline asthma prevalence rates and local pollutant data for State HIA in Florida. The local PM2.5 data in BenMAP can be used for other health outcome assessments, researchers will only have to update the prevalence rates for the health outcome used in their study. Estimation using local data will be less prone to uncertainties using National level data, the use of local data has been emphasized by several researchers. The study recommends future work in refining spatial grid resolution in BenMAP to zip code level to facilitate studies at neighborhood level. Another recommendation is to further design research to study SES in context to dietary changes and better understand social injustices in areas with diverse population. A population-based study in conjunction with Florida Asthma Coalition (FAC) asthma cases from doctors’ offices is recommended which will be able to control for misclassifications, and include weather and allergens in analysis while studying individual pattern of exposure and diet.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal