Tagged: Green Infrastructure

Has green gone mainstream?

Here’s some food for thought…….The following commentary blog was posted on the World Design Summit’s ‘Designing the Future’ website –  world design summit taking place over 10 days in Montreal in October, 2017. The event is described as, ‘an international gathering of diverse disciplines with a common focus: how design can shape the future.’ 

“Green has gone mainstream. But as green walls, rooftop farms, and tree covered skyscrapers become the norm in cities around the world, critics ask if these developments are simply the latest face of ‘greenwashing’. Environmental advocates such as Naomi Klein have long warned of corporations that attempt to mask questionable records by emphasizing green elements. Klein has challenged industrialists who partake in flashy, eco-conscious campaigns but do little to alleviate the impact of their businesses on the climate. Many companies spend more money convincing consumers that they are green than they do on actual green initiatives; some corporate green initiatives actually harm the environment.

Urbanists worry that greenwashing has spread to urban design and architecture by literally covering up buildings with plants. The vertical farms, plant-covered towers, and eco-villages that once seemed far-fetched are now not only possible but all the rage. Bringing greenery into the city may reduce emissions and improve air quality, but it does little to address the deeper causes of urban and environmental stress. Greening initiatives increase the economic value of places, risking displacement of economically vulnerable residents. Does a greenroof on top of a superstore help uninsured workers? What difference does a green tech-campus make if it requires hundreds of parking spaces?

One architect who questions greenwashing is Alejandro Aravena, director of the firm ELEMENTAL in Chile. At last year’s Venice Architecture Biennale, Aravena exposed the wasteful side of design by exhibiting 90 tons of detritus from the previous year’s event. He also tackles underlying challenges, by collaborating with communities to empower them to design affordable and sustainable housing for themselves. In this age of tree-covered skyscrapers, Aravena’s commitment to modest and even monotonous design stands out.

Questioning greenwashing demands that designers ask whether the green city must be a luxury for the privileged and whether sustainability initiatives accelerate inequality. Designers in all disciplines must look beyond rhetoric and aesthetics to evaluate the impact of environmental design. How can we, as designers, reconcile our role, which is closely linked with the market economy and over-consumption, with environmental and social awareness? Designers invested in truly sustainable practice are encouraged to submit a proposal for the topic “Questioning Greenwashing” at the Congress for the World Design Summit.”

The article is not attributed to any particular author but it would be interesting to hear your thoughts?  What’s your opinion in relation to #greenwashing? The article is illustrated by Stefano Boeri‘s proposals to build “forest cities” in Shijiazhuang, China plus an image of Bosco Verticale, Milan although the latter is not credited – (neither  design is referred to by name in the article). Both designs incorporate vegetation on the outer construction with the twin towers of Bosco Verticale – constructed with a $2.5 billion public-private investment as part of the redevelopment of Milan’s Porta Nuova district – housing 800 trees between 9 and 30 feet tall, over 4,000 shrubs, and 15,000 ground cover plants including vines and perennials.

The summit focuses on 6 key themes including ‘Design for Earth’ and 108 topics including ‘Questioning greenwashing’,

“Designers are sensitive to environmental issues and announce their willingness to conform their practices. However, beyond appearances and words, critical scrutiny is essential. How can we, as designers, reconcile our role, which is closely linked with the market economy and over-consumption, with environmental and social awareness?”

To read Naomi Klein’s, ‘The hypocrisy behind the big business climate change battle’ . Source: The Guardian, Sept, 2014.

naomi klein

Call for empirical evidence for climate resilient urban planning.

Regulating urban surface runoff through nature-based solutions – An assessment at the micro-scale.  Zölch,T, Henze, L, Keilholz, P & Pauleit, S.  Environmental Research, Volume 157, August 2017, Pages 135–14.

Key findings

  • Runoff after heavy rain events accounts for approx. 95% of total precipitation in highly sealed urban areas.
  • By enhancing water storage capacities green infrastructure reduces runoff by max. 14.8% compared to the baseline.
  • Green roofs and trees both show to be effective but due to different functions.
  • The reduction of runoff is larger with higher shares of green cover in the case area.


Urban development leads to changes of surface cover that disrupt the hydrological cycle in cities. In particular, impermeable surfaces and the removal of vegetation reduce the ability to intercept, store and infiltrate rainwater. Consequently, the volume of stormwater runoff and the risk of local flooding rises. This is further amplified by the anticipated effects of climate change leading to an increased frequency and intensity of heavy rain events. Hence, urban adaptation strategies are required to mitigate those impacts.

A nature-based solution, more and more promoted in politics and academia, is urban green infrastructure as it contributes to the resilience of urban ecosystems by providing services to maintain or restore hydrological functions. However, this poses a challenge to urban planners in deciding upon effective adaptation measures as they often lack information on the performance of green infrastructure to moderate surface runoff. It remains unclear what type of green infrastructure (e.g. trees, green roofs), offers the highest potential to reduce discharge volumes and to what extent.

Against this background, this study provides an approach to gather quantitative evidence on green infrastructure’s regulation potential. We use a micro-scale scenario modelling approach of different variations of green cover under current and future climatic conditions. The scenarios are modelled with MIKE SHE, an integrated hydrological modelling system for building and simulating surface water and groundwater flow, and applied to a high density residential area of perimeter blocks in Munich, Germany. The results reveal that both trees and green roofs increase water storage capacities and hence reduce surface runoff, although the main contribution of trees lies in increasing interception and evapotranspiration, whereas green roofs allow for more retention through water storage in their substrate. With increasing precipitation intensities as projected under climate change their regulating potential decreases due to limited water storage capacities. The performance of both types stays limited to a maximum reduction of 2.4% compared to the baseline scenario, unless the coverage of vegetation and permeable surfaces is significantly increased as a 14.8% reduction is achieved by greening all roof surfaces.

The authors conclude that the study provides empirical support for the effectiveness of urban green infrastructure as nature-based solution to stormwater regulation and assists planners and operators of sewage systems in selecting the most effective measures for implementation and estimation of their effects.


Urban green infrastructure as nature-based solution to regulate surface runoff becomes increasingly important, as climate change and urbanisation alter the urban water balance. The present study assessed the performance of two urban green infrastructure (UGI) types, trees and green roofs, on relevant hydrological processes, especially surface runoff. The two measures were applied in scenarios of different greening quantity and for heavy rain events of different intensities as projected for the future. This scenario approach revealed that both trees and green roofs contribute positively by interception, evapotranspiration and infiltration. Differences in their performance showed to be dependent on the greening quantity, share of permeable surfaces leaf area index (LAI) and finally, intensity of the rainfall event. Generally, their effectiveness remains low under heavy rain events, unless a significant proportion of the case area is greened to provide sufficient water storage capacities (Artmann, 2014).

For urban planning the presented results have practical implications for the selection of UGI types to reduce surface runoff volumes and in consequence reduce discharge loads, the sewage system has to handle. An effective nature-based solution increases the storage capacities within the area of interest as much as possible, while using open spaces that have not been used previously and/or while providing benefits to other areas of urban planning. Trees increase the storage capacity mainly by intercepting and evapotranspiring rainwater, their infiltration capacity is limited to the tree pits. But trees can normally not be implemented in large quantity in dense urban areas due to their requirements of open space. Green roofs on the other hand, provide storage capacity mainly by retaining rainwater in their substrates and can be implemented at larger scale on previously unused roof surfaces.

Furthermore, both types are multifunctional and can provide co-benefits for urban planning. The approach represents a first step in allowing planners as well as operators of sewage systems to estimate reductions in runoff volume when locally implementing UGI measures. These estimations could be further improved by integrating additional stormwater management practices and the drainage system in more detail into the modelling setup. Thus, conducting a larger systematic study of UGI scenarios would allow for including e.g. more UGI types, different species and LAI values as well as planting conditions. Such a study could enhance the provision of empirical evidence for climate resilient urban planning.


In March 2013 the Landscape Institute published an updated Mission Statement, ‘Green Infrastructure: An integrated approach to land management’. The document was described as,

“An opportunity to showcase a range of successful strategic GI work and completed
projects. The aim is to give public and private sector bodies, clients and natural and built environment professionals fresh insights into the benefits GI can bring by creating multifunctional landscapes and show how people can collaborate to deliver it.”

Nature-based solutions: flood management and policy development

Research:  Collentine, D. & Futter, M.N. (2016). Realising the potential of natural water retention measures in catchment flood management: trade-offs and matching interests. Journal of Flood Risk Management. DOI: 10.1111/jfr3.12269.

Natural water-retention measures, which ‘keep the rain where it falls’, have great potential to be used as part of flood-risk management plans. But their benefits for downstream urban areas can bring costs to the upstream agricultural areas where they are installed. The researchers suggest that we need new and/or improved policies and institutions to oversee the trade-offs and benefits for agriculture and flood management, and a better scientific understanding of the measures’ likely impact on urban flood risk.

The analysis, conducted by academics in Sweden, draws on various studies to discuss the many benefits of natural water-retention measures and how to encourage their uptake. Floods, which have caused annual economic losses of €4 900 million in Europe, are a serious problem. Natural water-retention measures could play an important role in managing floods, the researchers say, and help meet the goals of the EU’s Floods Directive and Water Framework Directive. These nature-based solutions store rainfall and allow it to evaporate back into the atmosphere to help prevent water flowing into urban areas, where it can cause the greatest damage.

Nature based water-retention measures are a key example of how green infrastructure can work alongside traditional grey infrastructure (e.g. flood gates). They take many forms, from small green roofs to large forests, and bring multiple benefits. As well as reducing flood risk, they can have value for biodiversity, recreation and water quality because they reduce soil erosion and can prevent agricultural pollution running into rivers.

However, this multi-functionality may also act as a barrier to their uptake. Because they bring benefits that fall under different policy areas, it is not necessarily easy for decision makers to determine who should pay for these measures. For some measures, the effect on flood risk may be an additional, secondary benefit — as in the case of agricultural buffer zones, which are primarily intended to reduce fertiliser run-off.

Alongside flood-management benefits, measures installed on upstream agricultural land can also lead to trade-offs, notably reduced crop yield. This loss occurs either because cropland is replaced by the measures or because soil in fields becomes too wet. A payment-for-ecosystem-services (PES) model could, therefore, be used to finance natural water-retention measures, possibly through national agri-environmental schemes. Research from the USA has indicated that it is less costly to pay farmers to temporarily flood their land upstream, than it is to pay for urban damage downstream.

Other barriers to widespread uptake of natural water-retention measures include specific knowledge gaps. There is plenty of evidence to show the effectiveness of individual natural water-retention measures, particularly in small catchments. Computer-modelling studies suggest natural water-retention measures could contribute to downstream flood risk reduction, but there is a lack of real world studies which show how to incorporate such measures into flood-risk management plans and their likely impact on downstream urban flood risk. Such studies are needed to encourage further uptake by decision makers and land managers.

The exact area of responsibility of decision makers with regard to flood-risk management also remains unclear. As such, water policy at the national level is accountable to EU water directives and national decisions must be consistent with the decisions made at the EU level. This is also true for regional-level policy, which is based on national policy and, similarly, local decisions are founded on regional policy. Unfortunately, this set of embedded decisions seems to break down with flood-risk management and has led to a lack of distinction between jurisdictions. Each jurisdiction attempts to reduce flood damage within a limited area and thus tends to focus on the use of preventive structural measures, such as dams or retaining walls, rather than measures to reduce flooding (1).

The authors recommend that institutional structures and mechanisms are created or enhanced to oversee the urban/rural trade-offs that natural water-retention measures may bring, to match potential costs with benefits and ensure an appropriate compensation scheme is put in place; for example, one which links PES with flood-risk management plans.

1. This shortcoming should normally be addressed by the inclusion of a river basin approach within the flood risk management plans: http://ec.europa.eu/environment/water/index_en.htm

Contact: dennis.collentine@slu.se

New evaluation tools for biodiversity and sustainable drainage system assessment.

Sustainable drainage systems (SuDS) could be improved for biodiversity and local people with the help of two new evaluation methods presented by a recent study. The methods, which assess the value of SuDS sites for wildlife habitat, carbon sequestration, recreation and education, are described by the study’s authors as cost-effective, quick and reliable, and could help designers plan and retrofit SuDS that are wildlife-friendly and socially inclusive.

Source: Mak, C., Scholz, M., & James, P. (2016). Sustainable drainage system site assessment method using urban ecosystem services. Urban Ecosystems. DOI:10.1007/s11252-016-0593-6. This study is free to view at: http://link.springer.com/article/10.1007/s11252-016-0593-6.


SuDS mimic nature to manage and treat storm water. There are various forms of SuDS which help prevent flooding and clean up contaminants; these include ponds, green roofs, artificial wetlands and absorbent pavements. The green infrastructure provided by SuDS is seen as an important way of helping EU Member States achieve good surface water status under the Water Framework Directive.


Fig 1. Rural conditions – impacts of urbanisation on a catchment. (Ciria)

In the UK, where this study was conducted, the Construction Industry Research and Information Association (CIRIA) has recently updated its influential SuDS manual (1), which provides guidance on the planning, design, construction, operation and maintenance of SuDS. This latest version promotes the design of SuDS design that provides a range of ecosystem services.

The evaluation methods presented by this study are intended to support this ecosystems-services approach (2). They can help designers understand and improve the value of a SuDS site. They also give designers a better understanding of which features (2) of a SuDS site provide which ecosystem services, to help guide new developments.


The first method considers which features provide biodiversity-related services, specifically habitat for wildlife and carbon sequestration. It is adapted from an existing method (3) and based on evidence that diverse vegetation, at various heights, is best for providing habitat. The method involves assessing which broad types of vegetation are present, such as trees and grasses, at which heights (e.g., upper canopy of a tree, low bush, long grass, cropped grass), and if there are any plants in water.

Designers can then give a SuDS site a score to indicate its potential for providing habitat and carbon ecosystem services. In general, points are given for every layer of vegetation (including aquatic plant species, if present). However, the method considers ecosystem disservices as well as services, and the scoring system deducts points for some layers; for example, cropped grass, which is unbeneficial for carbon sequestration. The presence of any built and impermeable layers at a site (e.g. concrete surface) also leads to points being deducted.

The second method considers which features contribute to recreational and educational ecosystem services. It assesses public accessibility to a site (both legal and physical), evidence of the site being used for educational purposes by community groups, educational signs, the distance to the nearest educational establishment, and recreational infrastructure (e.g. benches and footpaths). Again, ecosystem disservices are considered, so the presence of litter and dog faeces is also assessed, as well as bins, which help reduce these two problems. Each feature is scored on a scale of 0 to 3. Scores for recreational features and scores for educational features are combined separately to produce two total scores.

The researchers tested the two methods on 49 sites in and around the city of Manchester, UK. This revealed that large sites (over 5 500 m2) with permanent aquatic features such as ponds tended to be more capable of providing habitat and carbon sequestration services. Scores for habitat and scores for recreation were positively linked to each other. The researchers acknowledge that there is some subjectivity to the evaluation methods, but say that they provide the right balance of reliability, speed and cost-effectiveness.

Contact: miklas.scholz@tvrl.lth.se; m.scholz@salford.ac.uk


  1. http://www.ciria.org/Resources/Free_publications/SuDS_manual_C753.aspx
  2. Scholz, M., Uzomah, V., Almuktar, S., Radet-Taligot, J. (2013). Selecting sustainable drainage structures based on ecosystem service variables estimated by different stakeholder groups. Water, 5:1741–1759. DOI:10.3390/w5041741.
  3. Tzoulas, K., James, P. (2009). Making biodiversity measures accessible to non-specialists: an innovative method for rapid assessment of urban biodiversity. Urban Ecosystems, 13: 113–127. DOI:10.1007/s11252-009-0107-x.

At Home with Nature: Encouraging biodiversity in new housing developments

The London Assembly’s  latest report, ‘At Home with Nature: Encouraging biodiversity in new housing developments’ published in Jan 2017, delivers the latest findings from the Housing Committee which scrutinises the Mayor’s role and record in delivering the private, social and affordable homes London needs.

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There is a risk that London will see its biodiversity being squeezed or reduced as planners and developers try to increase housing density in the city. Nature provides physical, mental, social, environmental and economic benefits for city dwellers, but both flora and fauna are rapidly decreasing in UK cities. The Mayor has an important role in ensuring biodiversity is enhanced and new habitats are created, as London attempts to tackle the housing crisis.

Biodiversity is part of national, regional and local planning policies. Collectively, these policies provide a good overall strategic vision for providing for nature in London. Unfortunately, these policies are not always translated at ground level.

Some European cities explicitly recognise the importance of green infrastructure and the environmental, social and economic benefits it provides. Several cities have introduced a planning tool called a ‘green factor’ or ‘green space factor’ (GSF) to ensure a minimum level of greenery in new developments. This planning tool has increased levels of green space and improved resilience to flooding and climate change impacts in these cities.

There are inconsistences at borough level when it comes to approving planning applications. This is due to lack of ecology expertise within planning departments and other pressures, for example housing target pressures, which can impact on the decisions of the authority. Funding cuts have reduced the capacity of planning departments.

Developers are sometimes uncertain of the steps needed to promote biodiversity and therefore the cost of doing so. The historic emphasis on protecting key species sometimes worries developers and mean some avoid biodiversity entirely. However, some developers clearly do value biodiversity on their sites and include biodiversity adaptations and green infrastructure where it is feasible. The inclusion of biodiversity and green infrastructure in a site has been shown to increase the chances of receiving planning permission with fewer conditions, positively affecting prices paid and speeding up the rate of sales.

This report explores the current situation and offers some potential solutions to ensure that London maintains and improves on its current levels of biodiversity, as it continues to grow and change.


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London is still one of the greenest cities in the world but, in the rush to tackle the housing crisis, there is a risk that opportunities to protect and enhance local flora and fauna are being lost. In order to build the homes that London needs, a large proportion of these homes will be built on brownfield land and at higher densities. An increased housing density could lead to a more fragmented environment for nature, reducing biodiversity and access to nature for Londoners.

Although nature provides physical, mental, social, environmental and economic benefits for urban dwellers, both flora and fauna are rapidly decreasing in UK cities. The 2016 State of Nature report showed that, in the UK, 56 per cent of species are in decline and 7 per cent of urban species are threatened with extinction. For example, London’s hedgehog population has dropped by 50 per cent since 2000. This is a further concern for London government as nature can also improve the city’s resilience to climate change and can help mitigate issues associated with high density living, such as flooding and the urban heat island effect, thereby generating financial savings in the long term.

The Mayor has an important role in ensuring biodiversity is enhanced and new habitats are created. A large proportion of new homes will be built on public land and will be subject to Mayoral planning approval if they are of potential strategic importance to London. This means that the Mayor can, and should, push for higher requirements for biodiversity on these sites in order for planning permission to be granted.


  • RSPB, 2016, The State of Nature
  • Written evidence from the People’s Trust for Endangered Species
  • GLA, 2016, Mayoral planning powers

Does investment in green infrastructure provide economic returns?

Source: Vandermeulen, V., Verspecht, A., Vermeire, B. et al. (2011) The use of economic valuation to create public support for green infrastructure investments in urban areas. Landscape and Urban Planning. 103:198-206.

With increasing urbanisation and its subsequent negative effects on the environment, the need for green spaces is becoming increasingly recognised. Although it is difficult to define ‘Green infrastructure’, a network of open spaces, parks, waterways, trees and woodland that protect and enhance nature, and provide health and economic benefits, presents a possible solution to this problem. Decision makers need to know that investment in it will provide an economic return at both a regional and a community scale.

Using results from the EU VALUE project (1), the study produced a combined local-regional economic valuation model for assessing green infrastructure investment. At the project level, the study applied a cost-benefit analysis, using the concept of ‘Total Economic Value’, which attempts to capture the value of the different components of natural resources. Costs considered by this approach include land purchasing costs, design and construction costs and maintenance costs of the infrastructure, whilst benefits include production and regulating ecosystem services such as air quality improvement and climate change mitigation, as well as improved health from cycling, reduced accident risks, as well as recreational benefits. At the regional level, a ‘multiplier analysis’ was used, based on an input-output approach to consider not only the positive impact on local industry, but also on wages and the subsequent impact from better wages and job creation on the regional economy.

To illustrate how this two-tier model could be applied, the researchers used a case study of a proposed green cycle route in Bruges, Belgium, which is expected to lead to a 5% increase in cyclists. The example represents only a few aspects of multi-functional green infrastructure – an approach which is aimed at directly improving ecosystem health and resilience and contributing to conserving biodiversity (2). But it represents a type of project that contributes to the health and welfare of urban dwellers and brings environmental benefits to urban areas. Values were calculated for a 20 year timeframe. Examples of costs at the project-level were the construction of the bicycle road, indirect costs arising from tax increases and lost opportunity costs owing to farmers giving up land.

Evaluated benefits included the avoided car costs, tourist expenditure, improved traffic safety and positive health effects of cycling leading to lower health care costs and less absence from work. Alongside this were the environmental benefits effects of improved air quality and climate change mitigation. Using the cost-benefit approach, environmental benefits alone were estimated at €608,894 over 20 years, whilst the total value of green infrastructure at project level was estimated to be €1,707,169, which also included benefits from improved road safety, health and recreation. Regional additional effects were valued at €3,885,723, more than twice as high as the project effects. Most of the regional value is created by the multiplier effect of the investments in the project. The total value of the cycle belt is therefore €5,592,892, when project and regional values are combined over a 20 year period.

The researchers suggest that the model provides a useful complement to traditional cost-benefit approaches by highlighting the indirect economic benefits of green infrastructure. It can help convince stakeholders of the importance of investing in green infrastructure and allow policymakers to balance issues of community and economy growth, environmental protection and quality of life. They highlight that in addition to data limitations, the objectives of the evaluation will define or limit the inclusion of different types of benefits and costs in the evaluation exercise. If full benefits were included, such as stress reduction and emotional benefits, then the outcomes would be more positive, whereas if costs, such as automobile industry losses, were included, then the investment would seem less positive.

1. VALUE (Valuing Attractive Landscapes in the Urban Economy) is supported by the European Commission through the Interreg IVB programme. See: http://www.value-landscapes.eu
2. European Commission’s webpage on Green Infrastructure. See: http://ec.europa.eu/environment/nature/ecosystems/index_en.htm
Source: Vandermeulen, V., Verspecht, A., Vermeire, B. et al. (2011) The use of economic valuation to create public support for green infrastructure investments in urban areas. Landscape and Urban Planning. 103:198-206.

Contact: Valerie.vandermeulen@ugent.be

Barcelona Research: links between green infrastructure, exercise and urban mortality rates



Urban and Transport Planning Related Exposures and Mortality: A Health Impact Assessment for Cities. ­Environ Health Perspect; http://dx.doi.org/10.1289/EHP220

Researchers have estimated that, annually, almost 3 000 deaths (i.e. 20% of mortality) in Barcelona, Spain, are premature, and would be preventable if residents lived in urban environments that met international exposure recommendations for physical activity, air pollution, noise, heat and access to green spaces. The results emphasise the need to reduce motorised traffic, promote active and public transport, and provide adequate green space to encourage exercise and mitigate the impacts of environmental hazards in cities.

By 2050 almost 70% of people are projected to live in urban environments globally. Certain aspects of urban living, including contemporary car-centric city designs, contribute to a sedentary lifestyle and high levels of air pollution and noise, which are known to contribute to premature death. In addition, cities experience increased heat exposure due to human activities and heat-amplifying effects of the built environment.

Green infrastructure – such as parks, urban gardens and surrounding greenness – can reduce the impacts of these environmental risks and provides well-known benefits for physical and mental health.

In this study, researchers estimated the difference between actual and recommended levels of physical inactivity, exposure to air pollution, noise, heat and insufficient access to green spaces in Barcelona. Barcelona has one of the highest air pollution and noise levels in Europe due to high traffic density, with a high proportion of diesel vehicles, and an urban design of narrow street canyons (where streets are flanked by buildings on both sides) that are shielded by dense construction. The city centre can be up to 8 °C hotter than surrounding areas during summer months and only 7 m2 of green space is available per resident; green spaces provide benefits in heat reduction and can mitigate traffic noise and possibly air pollution.

The researchers modelled preventable premature mortality and the increase in life expectancy for Barcelona residents if international recommendations for performance of physical activity and exposure to air pollution, noise, heat and provision of green spaces were met.

The researchers used existing international exposure recommendations as follows: physical activity – 150 minutes of moderate intensity or 75 minutes of vigorous intensity aerobic activity per week (World Health Organization — WHO); noise – daytime noise levels not exceeding 55 decibels (dB) (WHO); air pollution – annual mean particulate matter less than 2.5 micrometers in diameter (PM2.5) not exceeding 10 micrograms per cubic metre of air (µg/m3) (WHO).

Despite no recommendation being available for temperature, it is believed that with changes to the urban plan, such as increasing urban greenery, reducing motorised traffic and improving building design, a cooling effect of up to 4 ºC can be achieved1. The recommendation on availability of green spaces was taken from the European Commission’s working group ‘Measuring, Monitoring and Evaluation in Local Sustainability2 and the WHO, who both recommend living within 300 m of green space greater than 0.5 hectares in size.

Data on current exposure levels for Barcelona residents were taken for: (1) physical activity, from the 2011 Barcelona Health Survey; (2) air pollution, from the European Study of Cohorts for Air Pollution Effects (ESCAPE LUR) 2012; (3) noise, from Barcelona’s strategic noise map, 2006 (4) daily mean temperatures for Barcelona from 2009–2014, from the European Climate Assessment and Dataset (Klein Tan 2002) and (5) green space land use, from Urban Atlas, 2007.

The results indicated that over 70% of adults in Barcelona are insufficiently active. Air pollution and traffic noise levels (average current exposure is 16.6 µg/m3 of PM2.5 for air pollution and 65 dB for noise) far exceeded the recommended levels. Summer temperatures in the city exceeded the calculated threshold level on approximately 100 days per year and one third of the population did not live within the recommended distance of a green space.

The researchers estimated that 2 904 premature deaths could be prevented annually if all recommendations were met. This is almost 20% of all annual natural deaths in the city. The largest share of preventable deaths was attributed to insufficient physical activity (1 154 deaths), followed by air pollution (659 deaths), traffic noise (599 deaths) and heat (376 deaths). Access to green spaces was estimated to have the smallest impact on reducing premature mortality (116 deaths).

If these premature deaths were prevented, residents could expect to live, on average, 360 days longer. This benefit to society is valued at around €9.1 billion annually (based on the value-of-statistical-life approach (VoSL) — the amount of money people are willing to spend to save a statistical life).

The researchers acknowledge that the combined effects of the different environmental hazards were not modelled, resulting in potential double counting of deaths. On the other hand, air pollution deaths may also have been underestimated, as certain pollutants, such as nitrogen dioxides, were not considered in this study.

The researchers also acknowledge the limited scientific evidence on the adverse health impacts of noise exposure and beneficial impacts of green spaces. They also point out that the contextual setting and underlying population parameters, such as the general health of the population, personal choices, motivation for behavioural change and time lags between a change and a benefit in any given location, affect human health and the risk of death.

The research, however, does contribute to the understanding of multiple environmental exposures and associated health impacts in an urban setting. The researchers recommend fundamental changes to urban and transport planning. In particular, the use of active and public transport as a means of integrating physical activity into daily life is encouraged and is believed to provide numerous health benefits. Policies to reduce motorised traffic and promote active and cleaner modes of transport should therefore be prioritised. Reinforcement of green infrastructure can also promote engagement in physical activity, mitigate air pollution, noise and heat and has been associated with improvements in mental health, biodiversity and community benefits.

1. Doick et al. (2014)Zhao et al. (2014)

2. Working Groups on Measuring, Monitoring and Evaluation in Local Sustainability, Expert Group on the Urban Environment. Towards a Local Sustainability Profile: European Common Indicators. Technical Report. European Commission, 2001.

Source: Mueller, N., Rojas-Rueda, D., Basagaña X., Cirach, M., Cole-Hunter, T., Dadvand, P., Donaire-Gonzalez, D., Foraster, M., Gascon, M., Martinez, D., Tonne, C., Triguero-Mas, M., Valentín, A. & Nieuwenhuijsen, M. (2016) Urban and transport planning related exposures and mortality: a health impact assessment for cities. Environmental Health Perspectives. DOI: 10.1289/EHP220.

Contact: natalie.mueller@isglobal.org