very good question. One of the myths that need to be exposed and citations discontinued. Even international organisations have been searching for the origin of that parameter and the closest was in minutes of a meeting but not at all an official study.

Thank you Francesco for sharing the EU standards, but there is still a problem of climate zones. In arid zones, greens are not the abundant nature as in Europe, the desert is. Historically in arid zones there were never abundant greens.

Greens in cities have taken different forms in different climate zones and cultures. The psychological benefits of exposure to greens is indisputable, but also to nature (see environmental psychology) and unfortunately nature other than greens is understudied. Research should be extended to include water bodies, icy landscapes and desert... and much more.  

Dear Francisco, there is a recent publication from the WHO which discussed various indicators of green spaces. The primary indicator recommended by the WHO is an accessibility index: a green space (0.5 ha, or 1.0 ha) within 300-m distance. You can check out the publication.

Urban green spaces and health - a review of evidence (2016)

http://www.euro.who.int/en/health-topics/environment-and-health/urban-health/publications/2016/urban-green-spaces-and-health-a-review-of-evidence-2016

The Great Myth!

... but successful! Almost all cities are below that threshold, so it has served as a good argument to increase the number (and area) of urban green spaces.

Dear friends, you can consult the following publication where the distance 300 m to any green space >5000 m2 is used as an indicator by EU. https://www.publimetro.cl/cl/metroamp/publimetro-tv/2017/11/16/lo-creen-la-ciencia-demostro-los-escuchan-reggaeton-menos-inteligentes.html

Dear Colleagues, the link in the last answer is not ok, the correct one is the following: https://www.gdrc.org/uem/footprints/eci_final_report.pdf

Apologies for any inconvenience. Best wishes. PC.

That supposed WHO standard is still circulating in academic papers, blogs and webpages! I also have looked in vain. One of the difficulties in using the measure of square metres of green space per capita is that it can count all green space, including private green space which is largely inaccessible. The EU, through Eurostat and other agencies, has collected data on accessibility and green infrastructure gain/loss over time. These may be more useful standards to apply.

I also have spent 2 hours for searching the original reference which states that 9 m2， and also ended with no clues.

Thanks for all the links to actual studies and reports that DO provide standards and guidelines. I've seen the 9m2 citation also and could not find it.

There's no any publication linking this data to WHO, it's a myth from web. For information only, the Brazilian Standards: "The Brazilian Society of Urban Arborization (SBAU) proposed as a minimum index for public green areas for recreation value of 15 m2 / inhabitant (SBAU, 1996)."

SOCIEDADE BRASILEIRA DE ARBORIZAÇÃO URBANA – SBAU. “Carta a Londrina e Ibiporã”. Boletim Informativo, v.3 , n.5, p.3, 1996.

While consulting for UN Habitat they found that the 9m2 myth was in the minutes of a meeting held at WHO. Never in any publication really. That is the closest they got to the origin of this citation. However, adopting any standard globally is problematic as it does not fit Arid Zones. EU or Brazil are places where greens are the natural landscape whereas there are other natural landscapes that do not include greens. This target and indicator of Quality of life in urban settlements needs articulation and elaboration.

It seems that more important than finding the origin study of the standard for green space (9m2 per capita) is that whether defining "STANDARD" for all cities in different countries a proper index for analyzing cities? For instance, whether for two cities in Europe and Africa that there are different climates the same green space must be considered?

Hi! that's true, I have been looking for that answer and never found an official source from WHO with the indicator of 9 m2 per capita of green space as it is mentioned in a lot of studies as the minimum recommended and they cited WHO documents as a source, all of them are false citations?

Green space has been in the focus of research because of an emerging interest in the impact it has on human health and well-being in urban areas. One problem identified in many studies of this area is that in many cases articles do not clearly define what green space was studied.

Having studied the extensive literature of the last two decades, it is found that there is some confusion as to what different researchers understand by the term "green space". A number of different spatial scales and resolutions are used to describe the range of green spaces used in these studies. Most studies evaluating small-scale relationships show that urban green space can positively affect health. However, this is not clearly confirmed by studies using larger scales, such as city scale and census unit rate.

Because it is difficult to have a single, prescriptive understanding of green space, it would be better to formulate a definition of green space for the context of a concrete research that includes both qualitative and quantitative aspects. So, having a fix quantitative standard seems to be useless if not misleading.

The source most cited for the 9 square meters of green space per capita is the WHO's Meetings report Urban Planning From evidence to Policy Action (2010) but having read it, the data isn't there. It's probably a cyclical citation situation that started with someone erroneously citing that as the source. Here's a link to the report: http://www.euro.who.int/__data/assets/pdf_file/0004/114448/E93987.pdf?ua=1

The WHO Europe Report: "Urban planning, environment and health" 2010, describes several methodological approaches which then are used as background information for the working groups devoted to developing and discussing, the most suitable indicators to be applied for describing adequately the urban situation in relation to environmental health risks and concerns.

The benefits and the challenges faced in relation to the provision of more green and public spaces are discussed in this report mainly as a request of local authorities. The working group suggested some parameters for assessing the performance of cities in providing their citizens with adequate green and recreational areas, among them: Green and recreational space in absolute figures (sqm) and in% of municipality surface, possibly % of change of green space proportion over the years. No specific rule that requests a minimum size for green spaces is mentioned.

In Bon Meeting, November 2010, experts from 35 countries of WHO European Region and three international institutions defined the minimum set of indicators for monitoring the commitments to reduce health effects of environmental hazards in children which were adopted at the Fifth Ministerial Conference on Environment and Health in Parma, Italy. The meeting selected 18 environmental health indicators addressing Parma conference commitments (The Fifth Ministerial Conference on Environment and Health, Parma, Italy, September 2010) for four Regional Priority Goals: (1) ensuring public health by improving access to safe water and sanitation; (2) addressing obesity and injuries through safe environments, physical activity and healthy diets; (3) preventing disease through improved indoor and outdoor air quality; and (4) preventing disease arising from chemical, biological and physical environments.

The background paper for Regional Priority Goal 2 contained six new indicators addressing Commitment (iv) “We aim to provide each child by 2020 with access to healthy and safe environments and settings of daily life in which they can walk and cycle to kindergartens and schools, and to green spaces in which to play and undertake physical activity. In doing so, we intend to prevent injuries by implementing effective measures and promoting product safety.” The 6 indicators are:

1. Population-weighted availability of green urban areas.

2. Population-weighted availability of sport and leisure facilities.

3. Access to public/green open spaces and sports/recreational facilities.

4. Proportion of children going to and from school by different transportation modes.

5. Injuries due to traffic accidents in children and young people.

6. Hospital admission due to unintentional injuries: drowning and falls.

Indicator 1 can be considered a standard of green space but the definition of this standard in this meeting is: "Proportion of individuals (of all ages) living within a specified distance from a public park, green space, recreational area or athletic or swimming facility.

Annerstedt et al. (2012), use 300m as "a specific distance" from a public green space (ANNERSTEDT, M., ÖSTERGREN, P.‐O., BJORK, J., GRAHN, P., SKÄRBÄCK, E. & WÄHRBORG, P.: "Green qualities in the neighbourhood and mental health – results from a longitudinal cohort study in Southern Sweden". BMC Public Health)

The 2016 WHO Report "Urban green spaces and health: A review of evidence" offers a review of evidence on the health effects of green space in urban areas and presents an approach to measuring urban green space.

In this report the indicator is defined as proportion of population living within 300m linear distance to the boundary of a green space. Two minimum sizes of green space are recommended 0.5 and 1ha. As there is not a consensus on the minimum distance, the report also recommends performing additional analysis for distances 200 and 500m.

I think that the WHO 2016 approach is one of the best tools we have to measure green space but the minimum distances and green space sizes should be tested in local conditions.

After seeing too many citations, I read the entire meeting report (from Urban Planning to Evidence to Policy Action) but I couldn't find any clues. The wrong citation seems to be very famous.

Actually, the standard was never reportd in the frame of WHO official docments. During the preparation of FAO Guidelines on urban and periurban forestry, we tried to find out the text referring to the cited standard but it was impossible. SO, the interpretation is like this. In 1968, Italy published the standards for urban development and 9 m2 was the figure for green spaces in new construction areas. Meanwhile, Italy team was quite active in WHO and there is a unoffical report from Italy to WHO board where is used the 9m2 standard. Then the success story of 9m2 began. In the last documents of WHO on public/green open spaces, they are strongly reccommended in the policies and planning actions of the cities but it is always reported an appropriate dimensional standard with the conditions of the cities where they need to be implemented. And I guess it is quite right like that: cannot compare Antofagasta in the Atacama desert to Bangui, in the equatorial forest.

I can´t find it, either. It´s probably a myth.

A list of indicators on Urban Green Spaces and recommendations about accessibility, included in WHO documents, can be found here: https://www.euro.who.int/__data/assets/pdf_file/0005/321971/Urban-green-spaces-and-health-review-evidence.pdf?ua=1

https://www.euro.who.int/__data/assets/pdf_file/0010/342289/Urban-Green-Spaces_EN_WHO_web3.pdf

I think that this figure is the result of several experiences in many countries that enjoy the existence of green areas

or the average , for example, we find that Germany has a per capita share of 50 m2, while developing countries such as Egypt are 1/2 m2 per capita.

I have also been looking for a confirmation of the WHO 9m2 reference, to no avail. Thank you Fabio Salbitano for the clarification on this issue! The mistake has been permeating through research articles, as well as EC and UN documents (e.g. https://tinyurl.com/y2yx897t, https://tinyurl.com/yxnuy67l).

Just adding to the comment by Zydi Teqja, regarding the WHO Urban Green Space Indicator (% of population living within 300m or less of UGS sized ≥0.5ha), the European Commission has also been using the same indicator in different contexts, such as in the European Green Capital project (https://tinyurl.com/y4qu5sfc) and the European Common Indicators - ECI (https://tinyurl.com/y3a9lt88).

Regarding the ECI, the linked document mentions on a footnote that both the European Environment Agency*, the DG Regional Policy, and the ISTAT (Italian Istituto Nazionale di Statistica) all use the concept ‘within 15 minutes’ walk’ to define accessibility.

* Check table 10.1 in chapter 10 of the original DOBRIS Assessment (need to download a ZIP file with HTML content at https://tinyurl.com/y2gq4syb).

Dear Luís Valença Pinto thank you very much for your information

Dear Fabio Salbitano can you recommend any reference of 1968 Italian standards for urban development where 9 m2 was the figure for green spaces in new construction areas. Thank you @Fabio Salbitani

I found in Russo & Cirella (2018), IDB (1997), and others, including mentioning specific WHO documents (Health Indicators of sustainable cities, 2021), without being possible to confirm in the figures or any study or good considerations behind them. Despite being accurate or not, it is very important to consider the quality of green spaces, their accessibility and their spacial distribution, among other criteria.

This document (Urban green spaces and health: A review of the evidence) does not discuss a "per capita" metric, but it provides a literature review and explains in detail how to analyze different regions within Europe. https://www.euro.who.int/__data/assets/pdf_file/0005/321971/Urban-green-spaces-and-health-review-evidence.pdf

I found it on an official WHO website last year, but it appears to have ben taken down since then.

Peta Brom, when you say that you found it on an official WHO website, are you saying that you saw the original source of the 9 m2 value, or did you see an 'indirect' reference to a document mentioning this? Please don't forget that, often, indirect references, done based on previous references from other documents, can be perpetuating unintended errors. As I stated before, I have found EU and UN documents referencing WHO documents regarding the 9 m2 per capita, but when I followed the trail and checked the respective documents, the value was nowhere to be found. In other situations, I have realized that sometimes I need to check for the original document to assess if the thing that I read in my source was in fact what was mentioned in the original source.

Please check the answer by Fabio Salbitano added on May 19, 2020, regarding the curious story of the 9 m2 saga. Basically, it is/was (?) an Italian standard, published in 1968. If not mistaken, the 9 m2 of green space are per capita and were applied for 'new' construction areas from 1968 onwards.

As Cláudio C. Maretti mentions, a normative and reductive value, which cannot possibly represent the optimal value everywhere, is less relevant than UGS quality, spatial distribution, and accessibility.

The document shared by Christie A. Cole is very interesting and relevant, even if mainly focused on the European context.

being an archiect I can address this kind of recommendations as of limited value.

There are too many factors: Number of sunny days, wind, temperature, amount of views, cultural issues. In Warsaw, Poland, onEs they aimed 12 and 8sqm, in Kiev , Ukraine/similar latitude/ 20sqm, in Tokyo it seems to be none/Alex Kerr Dogs and…/

Hola!

We added some ideas linked to this discussion in this publication: Article Comparing green spaces provision and accessibility indicator...

"In many countries, scientific articles and public policy documents refer to a UGS standard provision of 9–11 sq.m per capita (sq.m/inhab.; e.g. PNUMA, 2010; Martinico et al., 2014; Scopelliti et al., 2016; Goro and Mwasi, 2018; Unal and Uslu, 2018; Zhiqiang et al., 2020). In Chile, SIEDU establishes a provision standard of 10 sq.m/inhab. This standard has been widely used and was also included in the UN’s “Methodology for the Preparation of GEO Cities Reports” (UN Environment Program) which is widely applied in Latin America (PNUMA, 2010). It has been indicated, by some of the above-mentioned documents and others, that it is also a recommendation of the World Health Organization, however, to our knowledge this is not confirmed by any WHO document. It should be noted that there are also standards with higher thresholds, for example, Natural England (2010) uses 20 sq.m/inhab., and some Russian cities outline such, as has been reported by Haase et al. (2019).