Quality of life and air quality as core of urban health issues

If we ask ourselves about health issues in cities today, the question of urban environment quality is predominant, despite the Covid crisis. The quality of the living environment and air quality are the main concerns in terms of psychological and physiological impacts.

As far as air quality is concerned, the figures speak for themselves: it is estimated that fine particles are responsible for 800,000 premature deaths per year in Europe and nearly 9 million worldwide [2].

 

A priority issue for city inhabitants

When an opinion survey of 2,000 French citizens asked what they expect from the “city of tomorrow”, the results were unequivocal: 53% of those polled put first “a city that brings nature back to the heart of the city”, second “a city that does not pollute” and third “a city that offers a good mix between economic and social life, between work and housing”, far ahead of “a connected city”, “a zero waste city”, “an energy-efficient city” and many others.

Moreover, 58% of those surveyed do not agree with the statement : “Cities are increasingly pleasant to live in,” while 92% of them tend to agree with the statement “There is not enough nature in the city”. [3]

Urban scale solutions for more desirability and against pollution.

Without establishing a hasty correlation between the lack of nature in the city and dissatisfaction with the living environment and excess urban pollution, it is nevertheless worth noting that the increase in natural areas appears to be a solution to the dissatisfaction of city inhabitants.

So, once again, solutions to pathologies affecting city dwellers are to be found in the environment. But what solutions can be integrated massively into the urban ecosystem? And what could their impact be?

 

Natural or nature-inspired solutions

Some solutions enhance the living environment while improving health conditions in urban areas. This is the case for solutions based on nature. They are defined by the International Union for the Conservation of Nature (IUCN) as: “actions to protect, sustainably manage and restore natural or modified ecosystems to respond directly to societal challenges in an effective and adaptive manner, while ensuring human well-being and generating benefits for biodiversity”.

Let’s explore some of these solutions together:

• Trees, an evidence

In opposition to the hygienist theories that perceived them as an urban decoration, trees have been infused with values ever since they have been considered by a systemic approach coming from urban ecology. This consideration has led to numerous studies attesting to their effects.

According to ADEME, in street alignment, they reduce by 50% the concentration of fine particles in nearby habitations [4], a tree being able on average to trap 100 grams of fine particles per year [5] According to observations made in Angers, for 16 000 trees in alignment, 3000 tons of carbon are stored [6]

• Green roofs and facades.

Well known, these solutions are little praised for their impact on urban air pollution. However, in addition to the important capture of dissolved pollutants that they provide by filtering rainwater, the process of depositing directly from the air to plant surfaces also improves air quality.

According to a study carried out for the city of Manchester, in Great Britain, if the roofs of the city center were covered with grass, about 1.7 tons of fine particles would be captured, out of the 9 tons emitted each year. This is equivalent to a reduction in the order of 19% of in suspension pollutants [7]

• Street furniture that cleans up the environment: the example of the City Tree

16m2 of grass, a bench and a reservoir: this is the “City Tree” system. This type of solution makes it possible to bring the ecosystemic qualities of the vegetal even when it is difficult to plant (streets, mineral squares, etc.). This system, fed by rainwater, has a CO2 storage capacity equivalent to that of 275 trees, i.e. 240 tons over its lifetime [8].

City Tree installed in Brussels, Mont des Arts – Photo credit : Julien RENSONNET

These types of ecosystem service solutions offer many other complementary outcomes to the improvement of air quality. They help fighting heat island effects, improve the sustainable management of rainwater and contribute to the quality of the living environment.

 

Technical solutions

• Nanoparticles paint

Airlite is a paint based on nanoparticles of titanium dioxide that are activated by light to produce special ions, hydroxyl radicals, generally referred to as “nature’s detergents”. This paint eliminates bacteria and viruses on treated surfaces, reduces pollutants (such as NOx, SOx, NH3, CO) and lowers the temperature of painted surfaces.

Applied on 100m² of surface, the paint reduces atmospheric pollution in the same way as a 100m² forest surface [9]

A particularly interesting example of its application can be found in Mexico City, where a 2,000 m² surface area of large mural paintings neutralizes the equivalent of the toxic gases emitted by 60,000 cars each year.

Source : courtesy of the Boa Mistura collective  – credit : theartnewspaper.com

• Cultured photosynthesis

The Biosolar technology, developed by the start-up Arborea, relies on the photosynthesis of microscopic plants to eliminate greenhouse gases while generating breathable oxygen at a rate equivalent to that of a hundred trees for the deployment of a surface area equivalent to a single tree [10]

At the same time, the system produces a sustainable source of organic biomass from which nutritious food additives for plant-based food products are extracted. Although this solution may seem futuristic, it is nevertheless one of the possible answers to the challenge of relocating food production.

Due to this last function, the technology is currently being considered for rooftop or over-roof applications as well as for cultivation fields.

Credit: Imperial College London // Thomas Glover

 

Nature benefits and compensation through innovative solutions

Thus, many studies conducted over the last decade have allowed nature-based solutions to flourish. Their deployment on an urban scale makes up a set of short- and long-term solutions to transform the urban ecosystem.

By imagining their association with innovative technical solutions, better adapted to certain situations and urban contexts, we can imagine a version of the “city of tomorrow” with enthusiasm : more resilient, more sustainable and more desirable.

 

Sources :

1 : Traité des Airs, des Eaux et des Lieux, Hippocrate

2 : Article : La pollution de l’air tue deux fois plus que ce qui était estimé, Le Monde, 2019

3 : Enquête nationale « Les français veulent plus de nature en ville », NewCorp Conseil, 2017

4 : ADEME. L’arbre en milieu urbain acteur du climat en Région Haut De France , 2018.

5 : Bade, T., Smid, G. & Tonneijck, F. Cite Verte , 2011

6 : Cité Verte, Bienfaits du végétal en ville, 2014.

7 : Quantification of the Environmental Impacts of Urban Green Roofs, Andrew Francis Speak, 2013

8 : Article : City Tree de Bruxelles : invention révolutionnaire ou simple mobilier urbain esthétique ? RTBF, 2017

9 : Descriptif du produit : https://www.airlite.com/airlite-natural-paint/

10 : Article : World’s first ‘BioSolar Leaf’ to tackle air pollution in White City, London Imperial College, 2019

 

Written by Dylan El Omeiri.