Climate Emergency: Time to look at practical solutions to urban air quality problems
Following weeks of direct action by school climate strikers and the movement Extinction Rebellion, MPs have endorsed the motion to formally declare a climate and environment emergency. Environment Secretary, Michael Gove, accepted the situation that we face is “indeed an emergency” and expressed his hope that the parties will have a “civilised debate that combines a sense of urgency about the challenge in front of us and a determination to take action in the future.”
Cities are becoming more and more problematic areas, in most cases having the most dangerous levels of air pollution. UNICEF estimates that one in three children are growing up in UK cities with unsafe levels of particulate pollution. On average, children spend 40% of their time in the playground and on the school run, and 60% of that time they are exposed to tiny particles of black carbon. Exposure to this pollutant can stunt brain and lung growth, and cause long term breathing problems once it penetrates into the blood stream. UNICEF UK’s Director of Advocacy said, “Every day, thousands of children across the UK are setting off on a toxic school run that could impact their lifespan and contribute to serious long-term health problems.” Studies being carried out are finding that more and more schools are operating in dangerous levels of air pollution.
Urban Heat Island (UHI)
But schools are just the sharp end of the problem. Our Cities, being massive, condensed hubs of activity, quickly become Urban Heat Islands (UHI). A UHI is where an urban area is significantly warmer than surrounding areas, caused by human activity and the modification of land surfaces from natural to man-made materials.
The U.S. Environmental Protection Agency estimates that urban heat exposure killed more people between 1979 and 2003 than did hurricanes, lightning, tornadoes, floods, and earthquakes combined.
The Environmental Protection Agency lists the four main impacts of the Heat Island Effect as the following:
- Increased energy consumption
- Elevated emissions of air pollutants and greenhouse gases
- Compromised human health and comfort
- Impaired water quality
With this being a massive contributor to our dangerous levels of air pollution, it’s important to look into what causes these UHI’s, and the measures we can take to alleviate the impacts and respond to the climate emergency we now face.
Materials used for pavements and roofs are commonly dark surfaces which absorb considerably more solar radiation than rural areas and hold different thermal bulk properties and surface radiative properties. A decreased amount of vegetation also leads to a lack in evapotranspiration (sum of evaporation and plant transpiration), and a loss of the shade and cooling effect of trees. According to the US Forest Service, cities in the US are losing 36 million trees each year.
Additionally, high-rise buildings provide multiple surfaces for the absorption and reflection of sunlight with their glass and metallic facades, and therefore more efficiently heat the surrounding area. Another effect of these tall buildings is that they block the wind which inhibits cooling, preventing polluting particulate matter from dissipating. These airless streets that retain heat and pollutants are known as urban canyons.
Working towards a change in urban design to focus more on creating environmental solutions and a greater appreciation and awareness of sustainable architecture, ANS understand that it is a sizeable challenge to force a re-structure of the urban landscape, but we do believe we can influence cities to work with what they have.
It is clear that one thing that is needed is an increase in vegetation in our cities. Unfortunately, with space being increasingly precious, we can’t readily create gardens and plant trees. This is where the use of green roofs is so important. There may not be a lot of space on ground level, but with the sheer number of buildings there is huge potential for the use of living green roofs. Cities like London are working on increasing the installation of Living Roofs and Walls, and summarising how the landscape has developed with key case studies is this report authored by Dusty Gedge and Gary Grant: The London Green Roof Report 2019: Living Roofs & Walls from policy to practice.
With the large number of buildings also comes a lot of wasted vertical spaces. A Living Wall is a real solution, not only making use of wasted walls, but covering what was likely to be a reflective, or solar absorbing surface, and preventing further contribution to the UHI. Even more importantly, the plants play a big role in reducing emissions by filtering out pollutants from the air through their plant hairs and cuticles – parts that have a detoxifying function. The larger the areas covered, the better we will be able to bring temperatures down, significantly reduce air pollutants, and let our cities breathe again. A new study has concluded that correct placement of plants at street level can reduce the concentration of the harmful Nitrogen Dioxide as much as 40%, and microscopic particulate matter by 60%.
This belief has driven us to create a system that is versatile enough to help tackle the issues we face. In every application, our designs for the living wall change to meet the needs of the particular location, for example including bird boxes to increase biodiversity at this development in London, where there is an obvious lack of biodiversity and natural elements, or the plant species specifically selected to tackle the high levels of air pollutants next to a busy road at London Wall Place.
While Michael Gove MP, may have declared a climate emergency there will be no improvement until concrete actions are taken to improve our cities and the life chances of future generations. Simple, practical urban greening solutions aren’t the full answer but they can make a significant contribution to cleaning up our urban spaces and rebalancing urban eco-systems.