Green Spaces in Highly Urbanized Tracts Tied to Lower Prevalence of Chronic Respiratory Diseases: A Nationwide Study Across Levels of Urbanicity

Previous studies have found conflicting results between green space and respiratory diseases, possibly due to the use of generalized green space measures and the diverse urbanicity levels in which they were conducted. Few nationwide studies examined how urbanicity modifies the relationship between green spaces and respiratory diseases while considering the geospatial relation between green space and human population, population density, and accessibility. This study evaluates the relationships between population-weighted forest and open space exposure (inside and outside park), chronic obstructive pulmonary disease (COPD), and asthma in the contiguous United States. The COPD and asthma data were obtained from the Centers for Disease Control and Prevention. The green space exposure within an 800 m buffer was computed using National Land-cover Dataset and WorldPop Global Pop-ulation Data. The associations were estimated using spatial error models and adjusted for important covariates. We also performed stratified analyses by four urbanicity levels.Green spaces inside but not outside park were associated with a lower prevalence of COPD and asthma. We found that a 1 m2 increase in forest inside park was associated with a decrease of 3.57 and 2.97 cases per 100,000 population in COPD and asthma, and a 1 m2 increase in open space inside park was associated with a decrease of 4.82 and 7.66 cases per 100,000 population in COPD and asthma. A trend of an inverse relationship was observed across urbanicity: the beneficial associations occurred in highly urbanized tracts but not in the three less-urbanized tracts.Our results provide further evidence that nearby forests and open spaces inside park, particularly in urban areas, were tied to a lower prevalence of respiratory diseases in the US. The beneficial association suggests the necessity of ensuring access to nearby green spaces, especially those in parks, to promote respiratory health.