Improving the air quality of cities by developing a natural green skin…
According to the World Health Organisation (WHO), ambient air pollution – made of high concentrations of small and fine particulate matter – is the greatest environmental risk to health. The major components of Particulate Matter (PM) are sulfate, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. As the concentration of PM increases, air quality declines. This increases the risk of stroke, heart disease, lung cancer and respiratory diseases, including asthma.
The WHO’s Global Urban Ambient Air Pollution Database covers more than 4000 cities in 108 countries. In 2018 it revealed that 97% of cities in low and middle income countries with more than 100,000 inhabitants, do not meet WHO air quality guidelines. The guideline stipulates that Fine Particulate Matter PM2.5 should not exceed an annual mean value of 10 μg/m3 and Coarse Particulate Matter PM10 should not exceed 20 μg/m3. Their website provides an interactive map revealing the worst cities using calculated annual mean concentrations of particulate matter based on daily measurements.
Using the figures for the PM2.5 annual mean, in micrograms per cubic metre, some of the worst cities for air pollution in Latin America included in the database* are Coyhaique, Chile (64), Brasilia, Brazil (54), La Paz, Bolivia (44), Guatemala City, Guatemala (41) and Lima, Peru (39). Cities that faired better include Mexico City, Mexico (22), Bogota, Colombia (15) Buenos Aires, Argentina (12), and Rio de Janeiro, Brazil (11). All of the cities listed have annual mean figures in excess of the WHO air quality guidelines (which is 10).
* The data was collected over the year of 2016, apart from data from Rio which was collected in 2015, Coyhaique in 2014, and Brasilia and La Paz in 2013. Not all world cities are included in the database.
Cities around the world are looking for ways to reduce air pollution including cleaner technologies for industry, improved management of waste, improved urban planning, renewable power generation, and cleaner transport methods – encouraging electric or hydrogen vehicles while discouraging diesel, improving public transport and creating bicycle schemes with safer routes for cyclists.
Another way to improve air quality is to increase the amount of green coverage that can absorb pollutants and help to cool down cities. Bogota is one city from those listed that is embracing this method.
In 2011 the District Department of Environment in Bogota published the Technical Guide of Green Roofs in Bogota, generating an instrument for the citizens. An updated technical guide of green roofs was published in 2014, with the theme Una piel natural para Bogotá – a natural skin for Bogotá, with useful information for citizens with contributions from professionals in the sector for those who wish to implement these technologies. This campaign focused on providing information about sustainability, green roofs and vertical gardens and included types of experts, a list of plants, a maintenance plan, as well as health and safety regulations.
Hundreds of meters of vertical gardens were installed in Bogotá between 2011 and 2014 during this period. The hope is that this legacy continues and can begin to reduce the auditory and atmospheric pollution in the city in a sustainable way.
Santalaia is an eight story, high-end, residential building in the barrio of Rosales in Bogota. In 2013 the buildings architects, Exacta Proyecto Total, approached Bogotá based company Groncol – a company that specialises in designing and installing green walls. The company, comprised of an interdisciplinary team that includes biologists, engineers and architects, took approximately eight months to design, and a further eight months to install a green skin around the building, which showcases a total of 115,000 plants covering 3017m2 of the walls and roof. At the time of installing, this was one of the largest vertical gardens in the world.
A complicated aspect of the installation – essential for the ongoing maintenance – was the irrigation system. It is comprised of 42 irrigation sectors that are regulated according to humidity and solar radiation. Additionally, there is a treatment plant that recycles water left over from the wall as well as some gray water from the building.
The vertical garden of Hotel B3, installed in 2012 by Groncol, was the inspiration for the Santalaia architects. It was the first hydroponic wall of this magnitude in Latin America. The project consists of a wall that covers the entire western facade of the hotel. It has more than 360m2 of vertical garden.
The company claims to have planted more than 8 million plants throughout the country and worked on 200 projects installing vertical wall and green roof tops on prisons, hospitals, residential and commercial sites. According to Groncol the Colombian capital has approximately 32,000m2 of green roofs. Bogotá has more than 1100m2 of vertical gardens implemented in universities, shopping centers, business buildings and restaurants.
Below is an aerial view of Tuluá prison. It’s green roof was designed and installed by Groncol. The project is part of a modular design for a new generation of prisons in Colombia. The intention is to make a bioclimatic design in which the roofs play an important role for temperature reduction.
Further Information
Groncol is a company that specialises in creating sustainable green spaces. They propose, design and develop green projects to meet this objective. The company also offers a series of innovative products that accumulate social, environmental and economic benefits.
www.groncol.com
T: @Groncol I: @Groncol F: Groncol
World Health Organization (WHO) are the directing and coordinating authority on international health within the United Nations’ system. They aim to provide leadership on matters critical to health, shape research agendas and share valuable knowledge. They set standards and promote and monitor their implementation; articulate ethical and evidence-based policy options; providing technical support, and building sustainable institutional capacity; and monitor and assess health trends.
www.who.int
T: @WHO F: WHO
*Main article image is an aerial photograph of the Santalaia residential building in Bogotá Colombia ©Groncol
The Seattle City Hall has led the way by implementing a green roof project that has involved the planting of more than 22,000 pots of sedum, fescue, and grass.