Urban green spaces reduce instances of violent


Properly designed and maintained outdoor green space has the potential to reduce violent crime and gun violence, to make communities safer and keep residents healthier, a new study suggests.

Conversely, green space that is poorly designed and inadequately maintained can help crime take root and spread.

The findings come from a team of scientists that has assembled a big-picture review of research on the complicated relationship between nature and crime in urban areas.

They identified several patterns that can help inform public policy, guide urban design and promote neighborhoods that are safe and pleasant to live in.

The project came about because members of the research team had been touched by crime, either directly or indirectly.

“All of us had some sort of experience, personally or through family members. And we thought maybe we can do something about it,” said Hessam Sadatsafavi, PhD, of the School of Medicine.

“How to control violent crime is a polarizing issue. We are interested to see, as designers whose work is to shape the physical environment, if it’s possible for us to contribute to this conversation and to take some actions to see if we, personally, can contribute to reducing crime.”

The Weed of Crime Bears Bitter Fruit

The research, initiated at Cornell University, sought to synthesize the findings of many previous studies that looked at the effects of various forms of green space on crime and criminal behavior.

“We said, OK, we have to start by understanding what is out there in terms of theory, what other people have found,” Sadatsafavi said.

“Green space can be a source of or increase the risk of crime in a neighborhood through some mechanism, and it can also reduce the risk.

So why is that happening? Is there any way to find a solution to make the risk reduction more effective?”

The researchers initially considered more than 14,000 papers but ultimately winnowed those down to 45 done in the United States, which offered the most relevant insights into how access to nature might improve public safety.

The initial review was challenging because the topic is vast and can be approached from many angles. “You might talk about community gardens, you might talk about people’s lawns,” Sadatsafavi explained.

“People who do the studies might go out and count the number of trees on sidewalks, or examine satellite images. Or look at the number of vacant lots that were turned into green space.”

That, combined with the wide variety of crime examined and how it was reported, made it difficult for the researchers to draw specific conclusions. “But,” Sadatsafavi said, “there are definitely patterns.”

For example, nine studies looked at the effect of green space on gun violence. Six found that such interventions reduced crime, while three were inconclusive.

“There is evidence that greening interventions at the urban level reduces violent crime, specifically gun violence,” said Sadatsafavi, of UVA’s Department of Emergency Medicine.

The researchers initially considered more than 14,000 papers but ultimately winnowed those down to 45 done in the United States, which offered the most relevant insights into how access to nature might improve public safety.

“By looking at all these studies, we were able to propose possible pathways [to reduce crime and] put together an overall picture of why this is happening, both in terms of gun violence and in terms of overall crime rate.”

Using Nature to Reduce Crime

Sadatsafavi hopes that the researchers’ findings, outlined in a paper in the International Journal of Environmental Research and Public Health, will lead to community interventions that keep people safe, decrease crime and promote better quality of life.

“The dream scenario for me, personally, is to raise awareness about the effectiveness and the cost effectiveness of these strategies,” he said.

“Our next goal as a team is to develop design guidelines for, say, how a community garden or small community park should be designed, to improve the positive effects of the green space and provide practical, hands-on information for people who are in the field, whether landscape architects or people who are starting their own community garden.”

Globally, around two in three people are predicted to live in urban areas by 2050 (Revi et al., 2014). However, these levels of urbanisation are projected to increase social and health inequalities, with corresponding negative impacts on physical and mental health, wellbeing and social cohesion (Giles-Corti et al., 2016).

Though health and wellbeing have complex social determinants, a central hypothesis is that benefits to health and wellbeing can be achieved through increasing physical activity and social interaction at the neighbourhood scale and by enhancing people’s ability to participate in society.

This may be achieved by improving the mobility and social networks of the population through designing better social and physical infrastructure, including increasing and enhancing the provision of urban green space (UGS) (WHO Regional Office for Europe, 2016WHO Regional Office for Europe, 2017aWHO Regional Office for Europe, 2017b).

Urban green space includes dedicated recreational space such as public parks, and other types of green space and vegetation, for example, street trees and green roofs.

Therefore, provision and preservation of UGS in a rapidly urbanising global context is important for a range of health, wellbeing and social outcomes.

However, provision of adequate UGS is challenging due to housing, retail and commercial developments and transport infrastructure all competing for limited space.

Furthermore, increasing storm water flows and pollution loads created by impervious surfaces from roofs, driveways, and sidewalks can create considerable environmental and health challenges, such as flooding, water pollution and high air temperature, as well as threatening the condition of existing green space.

Nonetheless, there are opportunities to redesign UGS in order to improve liveability and sustainability, and an urgent need to address issues of loss and deterioration of UGS where populations are growing and the urban footprint expanding.

Maintaining (and in many cases increasing) green space quantity and quality in the face of increasing urbanisation is therefore a pressing global challenge, recognised in the UN Sustainable Development Goals (n.d.).

Research examining the public health benefits of access to green space is extensive and persuasive (Kuo, 2015Gascon et al., 2016Twohig-Bennett and Jones, 2018).

Physical, psychological, social, economic and environmental benefits are evidenced, although some reviews still report mixed findings and often low-quality evidence (Bedimo-Rung et al., 2005Bowler et al., 2010aBowler et al., 2010bLee and Maheswaran, 2010Lachowycz and Jones, 2011Bragg and Atkins, 2016Husk et al., 2016Song et al., 2016Twohig-Bennett and Jones, 2018).

For example, in the most recent systematic review and meta-analyses by Twohig-Bennett and Jones (2018) including 143 studies, there was statistically significant support for exposure to green space and health outcomes such as decreased heart rate (−2.57; 95% CI -4.30, −0.83), decreased risk of type II diabetes (0.72; 95% CI 0.61, 0.85), and all-cause mortality (0.69; 95% CI 0.55, 0.87).

However, the conclusions must be interpreted with caution due to high levels of heterogeneity for some meta-analyses and a proportion of studies of poor quality. However, such benefits are not necessarily equitable across all in society.

Some research suggests that the provision of UGS is associated with widening health and social inequalities (Cole et al., 2017), whereas other research suggests particular benefits for our most deprived populations (Mitchell and Popham, 2008Maas et al., 2009aMaas et al., 2009bMitchell et al., 2015Twohig-Bennett and Jones, 2018).

However, many of these arguments are based on observational evidence, and the impact of UGS interventions on equity is limited (Twohig-Bennett and Jones, 2018).

Many policymakers are advocating changes in the physical environment, including the provision of UGS, to support healthy populations (WHO Regional Office for Europe, 2006Benton et al., 2016Sallis et al., 2016NICE, 2018WHO Regional Office for Europe, 2018).

However, despite a substantial body of cross-sectional evidence and the attention given to the importance of physical environments (WHO Regional Office for Europe, 2006Sallis et al., 2016NICE, 2018), the evidence for the effectiveness of creating supportive physical environments through intervention research, particularly UGS, is inconsistent and of modest quality (Hunter et al., 2015Benton et al., 2016).

In some places, UGS receive significant investment for delivery and management, particularly from local authorities and through new development.

In others, constrained or reduced budgets for managing UGS limit opportunities for growth and improvement.

Therefore, in the context of rapid urbanisation and limited public spending, there is a need to determine how to optimally intervene to provide adequate exposure to UGS for all of society to realise the evidenced health, wellbeing, social and environmental benefits.

Using UGS as an intervention for multiple health, social and environmental benefits offers many advantages.

Unlike individual-level health promotion approaches, developing a supportive environment has the potential to achieve a greater reach by facilitating, population-wide improvements in health, and long-term effects.

Consideration of wider social and environmental benefits alongside health promotes the ‘multi-functionality’ of UGS interventions with impacts in multiple domains, demonstrating value more comprehensively. 

Maes et al. (2015) and WHO Regional Office for Europe (2006) encouraged local authorities to increase and improve the provision of UGS and most cities now have green space, open space or green infrastructure strategies.

However, there is little information about how to intervene to ensure adequate provision of, and exposure to, UGS that results in the greatest and most cost-effective benefits.

A recent review by Hunter et al. (2015) suggested that there was promising evidence for UGS interventions that combined a change to the physical green space with a promotion/marketing programme for increasing park usage and physical activity levels.

However, this review solely focused on physical activity behaviour, so there is a need to conduct a review to extend the current evidence base of UGS interventions for other health, social and environmental benefits in order to evidence the holistic nature of UGS interventions and make recommendations regarding future approaches.

This is particularly important given the emphasis on multifunctional UGS – there is a need to demonstrate the range of impacts from similar interventions to make the case for investment and the consideration of single benefits can hamper this endeavour.

Further, outcomes of health, wellbeing, social and environment are not independent but rather interact in a complex system. For example, the provision of urban street trees may impact positively on mental wellbeing and biodiversity measures yet increase air pollution levels due to reduced air circulation from canopy cover (Jin et al., 2014).

Also, provision of lighting in UGS may increases perceptions of safety and increase usage of the space yet reduce biodiversity due to light pollution causing birds to migrate from the area. By focusing on a range of outcomes, this review will help us better understand the multifunctional nature of UGS. Therefore, the aims of this study were three-fold:

1) to review and synthesise the evidence on the environmental, health, wellbeing, social and equity effects of UGS interventions;

2) to discuss the findings at an expert review panel;

3) to develop recommendations on UGS interventions to policymakers, practitioners and researchers.

University of Virginia Health System


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