Want to live long — look for an area with normal trees. Scientists have found that trees save lives from heart attacks, while lawns can even harm health

In modern residential areas in Belarus, tree plantings are practically absent; the landscaping consists of patches of lawns between parking lots. Photo: Minsk World Residential Complex developer

A new work by American scientists, published in the journal Environmental Epidemiology, for the first time detailed the influence of different types of vegetation on heart health, using artificial intelligence and a pedestrian's perspective, analyzed, as noted by the Telegram channel cybulinka.

A Pedestrian's Perspective

Researchers used deep learning algorithms to analyze 350 million Google Street View panoramas across the United States. The neural network literally parsed each image pixel by pixel, highlighting trees, grass, and other greenery (bushes or flowers).

Павялічыць

Artificial intelligence analyzes street panoramas: the algorithm divides the image into pixels, marking trees in dark green, grass in light green, and other vegetation (flowers and bushes) in yellow. This way, scientists were able to accurately calculate the proportion of each type of greenery seen by a pedestrian. Photo: Environmental Epidemiology

These data were compared with the health history of 88,788 participants in the large-scale "Nurses' Health Study", who were observed for 18 years. This approach allowed scientists to assess precisely the environment that people see daily outside their windows and during walks.

Trees Save, Grass — Not Always

The results of the analysis turned out to be ambiguous and, to some extent, counterintuitive.

Scientists recorded that a high percentage of visible trees within a 500-meter radius of a home was statistically associated with a reduced risk of cardiovascular diseases, with this link being most pronounced for ischemic heart disease.

At the same time, an increase in the area of lawns and other low vegetation, conversely, correlated with an increased risk of diseases. These findings remained valid even after accounting for factors such as income level, air pollution, population density, and patients' lifestyles.

Why Can a Lawn Be Harmful?

The explanation for this difference lies in physiological and ecological mechanisms.

Trees are significantly more effective at reducing stress through a direct psychophysiological response of the body, and also excellent at neutralizing urban noise, filtering air, and mitigating extreme heat thanks to their powerful shade.

Grass and small bushes practically lack such protective properties. Moreover, maintaining ideal lawns often requires the use of pesticides and regular operation of noisy internal combustion engine lawnmowers, which creates an additional burden on the ecology and nervous system.

Also, large grassy areas in the US are often indicative of low-density development areas where the urban environment does not encourage walking, forcing residents to rely on cars.

Павялічыць

Maps of greening density in New York, Chicago, and San Francisco, compiled based on street image analysis. Dark green indicates areas with maximum concentration of trees (up to 48% of image area), grass (up to 18%), or flowers and fields (up to 3%). Scientists used a 100-meter grid for maximum accuracy. Photo: Environmental Epidemiology

Researchers emphasize that the use of general satellite greenery indices may have previously masked this heterogeneity, mixing beneficial trees with potentially harmful factors associated with lawn maintenance.

Verdict for the Concrete Jungle

For residents of cities like Minsk, where in new districts all greening consists of grass and frail saplings between fields of asphalted parking lots, this study sounds like an alarming signal.

For public health, this means a need to revise urban greening strategies. Scientists urge politicians and architects to prioritize the development of "urban forests" and the preservation of mature trees, as investments in tree cover bring significantly greater medical benefits than the creation of ordinary meadows and flowerbeds.

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