Estimating The Impact of a Select Criteria Pollutant (PM2.5) on Childhood Asthma in Florida

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