The Effect of Urban Tree Canopy Cover and Vegetation Levels on Incidence of Stress-Related Illnesses in Humans in Metropolitan Statistical Areas of Texas
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Urban living is often characterized by a hectic pace which can result in a great deal of stress. One-third of Americans are reportedly living with extreme stress, with 75-90 percent of visits to primary care physicians being for stress-related problems. It is known that green areas have positive physiological impacts on human health. Past research found that visiting green areas lowers blood pressure, reduces headache and fatigue, improves mood and hastens recovery from stress. The main objective for this study was to determine if stress-related illness rates in regions of Texas were related to vegetation rates and tree canopy cover. Past research found that high blood pressure and heart attack are two major stress-related illnesses, so in this study, only these two stress-related illnesses were considered. Data on stress-related illnesses was collected from the Center for Health Statistics and the Texas Department of State Health Services for all 25 Metropolitan Statistical Areas (Metropolitan Statistical Areas or MSAs are counties or group of counties with a central city or urbanized area of at least 50,000 people) of Texas. Percent canopy cover was calculated for each MSA using the Multi-Resolution Land Characteristics (MRLC) National Land Cover Data canopy cover dataset. Vegetation rates for all the MSAs were examined for each MSA of Texas and were mapped for illustration using ArcView© 9.1 GIS (Redlands, CA) software. Visual relationships among the data were observed. Quantitative data was also analyzed using PASW® (SPSS statistical analysis software). When mapping stress-related illness rate into MSA regions of Texas, no clear trend was observed with vegetation rates or percent tree canopy cover when compared with stress-related illness rates. Semi-partial correlations were calculated to analyze the relationship between tree canopy cover and vegetation rate and stress-related illness rate variables after controlling the effect of external variables like income levels, age, population and ethnicity. There was no significant relationship found between stress-related illness data when compared to percent canopy and vegetation index for any the 25 MSAs of Texas.