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BACKGROUND: Compared nationally, rates of current asthma are lower among adults and significantly lower among adolescents in Florida. Compared statewide, Sarasota County has relatively clean air and low rates of asthma. Nevertheless, due to data availability, it is possible to assess the additional impact of aeroallergens and air pollutants on rates of respiratory-related emergency department (ED) visits among residents in this area.
METHODS: For 2005-2012, daily counts of ED primary complaints for Sarasota County residents treated in Sarasota County facilities were obtained from the Florida Agency for Healthcare Administration. Visits were classified as all respiratory disease (ICD-9 code 460-519), asthma (ICD-9 code 493), and non-asthma (ICD-9 code 460-519 excluding 493). Daily climate data were obtained from the Sarasota Bradenton Airport through the National Climatic Data Center. Daily total pollen was collected by Mary Jelks, MD and used with permission from the American Academy of Allergy Asthma and Immunology. Observed highest daily 8-hour ozone and 24-hour PM10 data from Paw Park were obtained from the Florida Department of Environmental Protection. Significant interactions were detected between month and all environmental predictors. All analyses were stratified by month. Daily ED visits were modeled as the dependent variable. Poisson regression was used to individually test the association between pollen, ozone, PM10, when adjusting for maximum temperature and precipitation. P-values with significant positive effect are reported.
RESULTS: Pollen was significantly associated with all respiratory visits during hotter months (April – September) and December (all p-values ≤ 0.0025). Non-asthma respiratory visits mirror this trend (all p-values ≤ 0.001), while pollen was only significant for asthma visits in April (p<0.0001) and August (p=0.048). Highest 8-hour ozone was significantly associated with all respiratory visits during January (p=0.0332) and February (p=0.0026), non-asthma respiratory visits during January (p=0.0359) and February (p=0.0169), and asthma visits during February (p=0.0246), with very large effects in some cases. During February, highest 24-hour PM10 was significantly associated with all respiratory visits (p=0.0007) and non-asthma respiratory visits (p= 0.0005) but not significant for other months or for asthma visits. Additional effect modification is suspected between air pollution and climate during other months.
CONCLUSIONS: There is a complex relationship between aeroallergens, air pollutants, and climate. Modeling the impacts of environmental predictors individually on respiratory health outcomes is the first step to quantifying contributions to observed disease burden. Further analyses examining the combined effects of these environmental predictors on health outcomes are needed and on-going.