Urban living has long been linked to higher stress levels, increased pollution exposure, and greater risk of chronic diseases such as heart disease. While green spaces are often promoted as a solution to these challenges, new research suggests that not all greenery offers the same health benefits. According to a recent large-scale study, trees stand out as a powerful protector of heart health for people living in cities, while grass and other low-lying greenery may not provide the same advantage.
This emerging evidence has major implications for urban planning, public health policy, and individual lifestyle choices. Understanding how different types of vegetation influence cardiovascular health can help cities design healthier neighborhoods and help residents make informed decisions about where they live.
Heart disease remains the leading cause of death in many countries, particularly across the Western world. Urban environments can increase cardiovascular risk due to factors such as air pollution, noise exposure, heat retention, sedentary lifestyles, and chronic stress. While medical treatment and lifestyle changes are essential, researchers are increasingly exploring how environmental factors influence heart health on a population level.
Green spaces have long been associated with improved mental well-being, increased physical activity, and lower rates of chronic illness. However, most previous studies treated all vegetation as equal, grouping trees, grass, shrubs, and parks into a single category called green space. This broad approach may have hidden important differences in how specific types of greenery affect health.
A new study published in the journal Environmental Epidemiology takes a more detailed look at urban vegetation and its relationship to heart disease. Researchers analyzed over 350 million street-level images from urban areas across the United States. Using artificial intelligence, they assessed what pedestrians actually see in their daily environments rather than relying solely on satellite imagery.
The research team then compared these visual greenery estimates with health data from nearly 89,000 women participating in the long-running Nurses Health Study. By examining the amount and type of vegetation within 500 meters of each participant’s home, researchers were able to identify patterns linking specific greenery types to cardiovascular outcomes.
The findings were striking. People living in urban neighborhoods with a higher percentage of visible trees had a 4 percent lower risk of developing heart disease. While this reduction may seem modest, experts emphasize that even small decreases in risk can translate into significant public health benefits when applied across millions of people.
Trees offer a unique combination of environmental benefits that directly and indirectly support cardiovascular health. Their tall canopies provide shade, reduce ambient temperatures, and mitigate the urban heat island effect. Trees also filter air pollutants such as fine particulate matter and nitrogen dioxide, both of which are known contributors to heart disease.
In addition, tree-lined streets tend to reduce noise pollution and encourage walking, social interaction, and outdoor activity. These factors can lower stress levels and promote healthier behaviors, further supporting heart health.
Perhaps the most surprising finding of the study was that grass and shrubs were associated with a higher risk of heart disease. Areas with more visible grass were linked to a 6 percent increase in heart disease risk, while bushes and shrubs were associated with a 3 percent increase.
Researchers caution that this does not mean grass or shrubs are inherently harmful. Instead, the results suggest that these types of greenery may lack the protective qualities offered by trees, or they may introduce unintended negative effects.
One possible explanation involves maintenance practices. Lawns and landscaped shrubs often require regular mowing, trimming, and pesticide use. These activities can contribute to air pollution, chemical exposure, and noise, all of which may negatively impact cardiovascular health.
Grass and low-lying vegetation also provide less shade and cooling than trees, offering limited protection against heat exposure. In hot urban environments, excessive heat is a known trigger for cardiovascular strain, particularly among older adults and those with existing health conditions.
A key strength of this study lies in its use of street-level imagery. Traditional satellite images capture greenery from above, but they fail to reflect what residents actually experience on the ground. A neighborhood might appear green from the sky while offering little shade, minimal tree cover, or limited visual relief at street level.
By analyzing images from sources such as Google Street View, researchers were able to measure the greenery that pedestrians encounter during daily activities like walking, commuting, or running errands. This perspective provides a more accurate picture of how urban environments influence health on a day-to-day basis.
The study’s findings suggest that urban greening strategies should prioritize tree canopy preservation and expansion rather than focusing solely on lawns or decorative landscaping. Planting and protecting mature trees may offer greater cardiovascular benefits than large grassy areas that lack shade and ecological function.
Urban forestry programs, zoning policies, and infrastructure projects can all play a role in increasing tree coverage. Preserving existing trees is particularly important, as mature trees provide far greater environmental benefits than newly planted saplings.
Public health experts emphasize that community-level environmental changes can complement individual lifestyle interventions. Improving neighborhood design may help prevent heart disease before it develops, reducing the burden on healthcare systems and improving quality of life.
Access to tree-lined streets and shaded neighborhoods is not evenly distributed. Lower-income communities and historically marginalized populations often have fewer trees and higher exposure to pollution and heat. These disparities contribute to unequal health outcomes, including higher rates of cardiovascular disease.
Expanding urban tree canopy in underserved areas could help reduce health inequities while also improving neighborhood aesthetics, property values, and climate resilience. When implemented thoughtfully, tree-planting initiatives can deliver social, environmental, and health benefits simultaneously.
For individuals living in cities, this research highlights the importance of environmental context in long-term health. While personal choices like diet, exercise, and medical care remain critical, the surrounding environment also plays a meaningful role.
When choosing a place to live, factors such as tree-lined streets, shaded sidewalks, and nearby parks with mature trees may offer more than aesthetic appeal. These features may contribute to lower stress, cleaner air, and improved cardiovascular health over time.
Residents can also advocate for greener neighborhoods by supporting local tree-planting programs, community gardens with tree components, and policies that protect existing urban forests.
While this study provides valuable insights, researchers emphasize the need for additional investigation. Future studies could explore how specific tree species, canopy density, and maintenance practices influence health outcomes. More research is also needed to understand how greenery affects different populations, including men, children, and older adults.
Understanding the mechanisms behind these associations will help cities design smarter, healthier environments tailored to the needs of their residents.
Not all green spaces are created equal when it comes to heart health. This new research suggests that trees play a uniquely protective role for urban dwellers, while grass and shrubs may not deliver the same cardiovascular benefits. By shifting the focus from generic green space to meaningful tree canopy, cities have an opportunity to improve public health at scale.
As heart disease continues to place a heavy burden on individuals and healthcare systems, even modest environmental improvements can make a meaningful difference. Investing in trees may be one of the simplest and most effective ways to build healthier cities for the future.
University of California-Davis, news release, January 21, 2026
Study reported in Environmental Epidemiology, February 2026
This article is for informational and educational purposes only. Statistical associations described here reflect population-level trends and do not apply to individuals. Health outcomes vary based on personal medical history, genetics, lifestyle, and environmental factors. This content does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for personalized medical guidance.
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