Summary: A significant link between the spatial distribution of urban greenspace and mortality risk has been established in a new study.
Source: Texas A&M
Some community parks are square, a reflection of the city block where they’re located — but irregularly shaped parks reduce the mortality risk of residents who live near them, concluded a study by Huaquing Wang, a Ph.D. Urban and Regional Sciences student and Lou Tassinary, professor of visualization.
“Nearly all studies investigating the effects of natural environments on human health are focused on the amount of a community’s green space,” said the scholars in a paper describing their project. “We found that the shape or form of green space has an important role in this association.”
Their paper was published in the Nov. 2019 issue of The Lancet Planetary Health.
In the study, Wang and Tassinary performed statistical analyses of Philadelphia land cover data to assess links between landscape spatial metrics and health outcomes.
They found that residents in census tracts with more connected, aggregated, and complex-shaped greenspaces had a lower mortality risk.
“Our results suggest that linking existing parks with greenways or adding new, connected parks might be fiscally accessible strategies for promoting health,” said Wang and Tassinary.
“We showed that the complexity of the park shape was positively associated with a lower risk of mortality,” they said in the paper. “This association might be attributable to the increased number of access points provided by complex-shaped green spaces.”
Irregularly shaped parks are either designed that way or shaped by the parcel they’re established in, said Wang. Lower mortality risk wasn’t associated with any particular form, but the data supports the idea that the more complex the park shape, the better, she said.
The relationship between park shape and mortality is important to city designers and planners who seek to create healthier living environments, they said in the paper.
“Our findings bring us closer to understanding the mechanisms underlying the protective effects of green space on mortality,” they said.
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Effects of greenspace morphology on mortality at the neighbourhood level: a cross-sectional ecological study
Background The association between urban greenspace and mortality risk is well known, but less is known about how the spatial arrangement of greenspace affects population health. We aimed to investigate the relation between urban greenspace distribution and mortality risk.
Methods We did a cross-sectional study in Philadelphia, PA, USA, using high-resolution landcover data for 2008 from the Pennsylvania Spatial Data Access database. We calculated landscape metrics to measure the greenness, fragmentation, connectedness, aggregation, and shape of greenspace, including and omitting green areas 83·6 m2 or smaller, using Geographical Information System and spatial pattern analysis programs. We analysed all-cause and cause-specific mortality (related to heart disease, chronic lower respiratory diseases, and neoplasms) recorded in 2006 for 369 census tracts (small geographical areas with a population of 2500–8000 people). We did negative binomial regression and principal component analyses to assess associations between landscape spatial metrics and mortality, controlling for geographical, demographic, and socioeconomic factors.
Findings A 1% increase in the percentage of greenspace was predicted to reduce all-cause mortality by 0·419% (95% CI 0·050–0·777), with no effect on cause-specific mortality. All-cause mortality was negatively associated with the area of greenspace. A 1 m2 increase in the mean area of greenspace led to a 0·011% (95% CI 0·004–0·018) fall in all-cause mortality and a 0·019% (0·007–0·032) decrease in cardiac mortality; considering only green areas larger than 83·6 m2 would contribute to a 0·002% (95% CI 0·001–0·003) decrease in all-cause mortality and a 0·003% (0·001–0·006) reduction in cardiac deaths. Census tracts with more connected, aggregated, coherent, and complex shape greenspaces had a lower risk of all-cause and cause-specific mortality. The negative association between articulated landscape parcels and all-cause mortality varied with age and education, such that the relation was stronger for census tracts with a higher percentage of older and less well-educated adults.
Interpretation A significant modest association exists between the spatial distribution of greenspace in cities and mortality risk. The overall amount of greenspace alone is probably failing to capture significant variance in local health outcomes and, thus, environment-based health planning should consider the shape, form, and function of greenspace.