Inequalities in green space linked to preventable deaths in urban areas

Study reveals that increasing green space in deprived urban neighborhoods could significantly reduce preventable deaths, highlighting the need for targeted public health investments.

​​​​​​​Study: Inequality in green space distribution and its association with preventable deaths across urban neighbourhoods in the UK, stratified by Index of Multiple Deprivation. Image Credit: doublelee/Shutterstock.com

In a recent study published in the Journal of Epidemiology & Community Health, a group of researchers examined the relationship between green space (GS) availability, deprivation levels, and preventable death rates across urban neighborhoods in the United Kingdom (UK).

Background

Investment in GS in urban areas may reduce preventable deaths and offer multiple health, environmental, and economic benefits. Exposure to GS is linked with lower mortality and morbidity from chronic diseases, improved mental health, cognitive functioning, and reduced obesity.

These health benefits stem from increased opportunities for exercise, social interaction, relaxation, and enhanced social cohesion. Environmentally, GS can reduce the urban heat island effect, reduce air and noise pollution, and promote biodiversity.

Economically, GS can lower cooling costs and increase property values. Further research is needed to identify geographic and socioeconomic priorities to optimize GS-related health benefits.

About the study

In England and Wales, the primary units were middle-layer super output areas (MSOAs), while Scotland utilized intermediate zones (IZs), and Northern Ireland used super output areas (SOAs).

These units vary in population size, with MSOAs in England and Wales averaging around 7,600 and 7,200 people, IZs in Scotland around 4,000, and SOAs in Northern Ireland approximately 2,000. Each boundary is mutually exclusive, ensuring clear division and comparability across areas.

Preventable deaths, the study's dependent variable, include causes like ischemic heart disease and certain cancers, which can be reduced through public health interventions. Data sources varied across regions, with figures provided by national statistical offices in Scotland and Northern Ireland. Calculations based on the Organisation for Economic Co-operation and Development (OECD) lists were used for England and Wales.

The study also included various independent variables. Deprivation levels were assessed using the Index of Multiple Deprivation (IMD), with values adjusted for aggregation to the geographic unit used in each region.

Additional variables like grassland and woodland coverage were sourced from the UK Centre for Ecology & Hydrology, with urban or rural classifications from the Office for National Statistics Census data. Demographic data, including population density and median age, came from mid-2015 estimates for England, Wales, and Northern Ireland and mid-2017 estimates for Scotland.

Data analysis utilized descriptive statistics and concentration curves to assess GS inequality. Regression models, specifically negative binomial regression, analyzed the impact of various factors on preventable deaths, focusing on urban areas and stratifying results by deprivation quintiles. Analyses were conducted using STATA version 15.0.

Study results

In examining the characteristics of GS across the UK, Wales had the highest median percentage of GS at 45%, followed by Northern Ireland (24%), England (21%), and Scotland (16%). Across all four countries, urban areas showed significantly lower percentages of GS compared to rural areas, highlighting notable differences in GS availability based on settlement type.

In England, Scotland, and Northern Ireland, the distribution of GS in urban areas was significantly skewed, with more deprived neighborhoods having less access to GS. This unequal distribution was evident as GS levels in these urban areas deviated notably from what would be expected in an equal distribution model.

In contrast, rural areas in these countries exhibited a more balanced GS distribution across neighborhoods, regardless of deprivation level. Wales presented a unique pattern, with GS distributed more equitably across both urban and rural neighborhoods of varying deprivation levels, suggesting fewer disparities in GS access.

The concentration index values, which measure the inequality of GS distribution, were highest in England, followed by Northern Ireland and Scotland, indicating a strong relationship between GS distribution and deprivation levels in these areas.

In Wales, however, the concentration index was notably lower, further reflecting a more even distribution of GS relative to deprivation levels.

Analyzing the association between GS and preventable deaths in urban areas, results revealed that in England, Scotland, and Northern Ireland, an increase in grassland was associated with a significant reduction in avoidable deaths within the most deprived neighborhoods.

In England, a 1% increase in grassland corresponded with a 37% decrease in annual preventable deaths, while in Northern Ireland and Scotland, a 1% increase was associated with reductions of 37% and 41% in five-year accumulated preventable deaths, respectively. This trend underscores the potential health benefits of GS investment in more deprived urban areas in these countries.

In Wales, however, the percentage of grassland showed no significant association with preventable deaths. Additionally, across Scotland, Northern Ireland, and Wales, there was no substantial link between woodland area and preventable death rates.

In England, the associations between woodland area and preventable deaths were observed only in neighborhoods within the third and least deprived quintiles, suggesting that the impact of woodland on health outcomes may vary according to the level of deprivation.

Conclusions

To summarize, this study highlights two main findings. First, significant inequality in GS distribution was observed among urban neighborhoods with varying deprivation levels across the UK, except in Wales, where GS distribution was more equitable.

More affluent areas generally had higher GS availability. Second, in the most deprived urban areas of England, Northern Ireland, and Scotland, a higher percentage of grassland was significantly associated with fewer preventable deaths.

This association was not observed in Wales, suggesting equitable GS distribution may contribute to health benefits.