Study Explores Associations Between Access to Urban Blue and Green Spaces and Early-Stage Heart Disease

By Erin Frick 

ALBANY, N.Y. (Sept. 26, 2024) — Heart disease is the leading cause of death in the United States and globally. Racial disparities in cardiovascular disease are well documented, with Black individuals often experiencing a higher disease burden compared to non-Hispanic white individuals.  

Access to natural “blue” and “green” spaces like rivers, lakes and forests helps facilitate physical activity and stress management, both of which support cardiovascular health. However, a new Circulation study led by the University at Albany's Kai Zhang and Lifang Hou from Northwestern University suggests that not all green spaces confer uniform health benefits.

The study is the first to examine the relationship between long-term exposure to green and blue space and early-stage cardiovascular disease. 

“Here, we investigated how health benefits associated with access to nature vary with race and socioeconomic status in four major U.S. cities,” said Empire Innovation Associate Professor Kai Zhang of UAlbany’s College of Integrated Health Sciences. “We found that living closer to rivers and in areas with more vegetation cover were generally linked to better heart health among Black participants and people living in socioeconomically deprived neighborhoods. However, we also found that closer residential proximity to major parks was linked to higher artery calcification, an early indicator of heart disease, for residents in more disadvantaged neighborhoods. One possible explanation is that poor park conditions and safety concerns in these neighborhoods may discourage park use, preventing residents from fully benefiting from the parks.

“This finding highlights the reality that the quality of green space matters, and environmental factors associated with inner city living can outweigh the benefits of living close to parks. It is critical that racial composition and socioeconomic status be considered when developing public health interventions aimed at leveraging natural environments to reduce cardiovascular disease.”

Measuring proximity to nature vs. heart health

The research drew data from the CARDIA (Coronary Artery Risk Development in Young Adults) study— a longitudinal cohort study initiated in 1985-86 that recruited Black and white adults aged 18-30 to participate in physical exams over 25 years. Participants hailed from four U.S. cities: Birmingham, Ala; Chicago; Minneapolis; and Oakland, Calif.

The sample for this analysis included 1,365 Black and 1,555 white participants who completed the year-25 CARDIA follow-up exam. 

Arterial plaque buildup, known as coronary artery calcification (CAC), was measured via CT scans to assess participants’ cardiovascular health. Plaque is the accumulation of substances like cholesterol, fat, calcium and cellular waste products in our veins. High CAC is associated with a higher risk of developing cardiovascular disease. 

The researchers measured participants’ access to green and blue space over time by looking at their residential addresses at multiple time points. For each geotagged address, four landscape-level factors were assessed: amount of surrounding vegetation cover, amount of surrounding water cover, distance to the nearest river, and distance to the nearest major park. 

The team used generalized estimating equation regression models to draw connections between exposure to blue and green spaces and artery calcification, paying close attention to whether these associations varied by race and neighborhood socioeconomic status.

Not all green spaces are equal 

Among Black participants, living closer to a river, and among higher vegetation cover, were both linked to reduced coronary artery calcification. Among participants residing in economically deprived neighborhoods, greater green space cover was similarly associated with lower coronary artery calcification. 

These findings support the notion that general greenness and proximity to water bodies are beneficial for heart health. 

However, the team also found that specifically living closer to a major park was linked to higher coronary artery calcification. This suggests that factors associated with living in deprived urban neighborhoods outweigh the potential benefits of park proximity. 

“Living close to an urban park does not inherently mean that it is a useful resource to support health,” said Zhang. “Other factors associated with inner city living can cancel out the benefits of park access. Environmental stressors like pollution, poor air quality, extreme heat and insufficient access to fresh food and medical services all contribute to poor heart health. Plus, parks that are poorly maintained, inadequately lit or otherwise thought to be unsafe are simply not viable resources for exercise and stress relief. 

“Natural environments hold great potential as a public health intervention to reduce racial and socioeconomic disparities in cardiovascular health. Yet, only safe, high quality green spaces, accompanied by other health resources, will yield meaningful benefits. Urban planning must take this reality into account in order to truly serve diverse communities and promote health equity.”

Read the full study here.