With the quality of our air becoming a huge health concern in our cities and urban areas, we keenly support using organic methods to counteract the effects of pollution for the benefit of our health and well-being.
With ‘Clean Air Day’ on 20 June 2019, we have decided to mark the occasion by bringing you some suggestions for turning your garden into an oasis of clean air.
As you may already know, however, tackling air pollution through planting shrubs, hedges and trees requires more thought than simply planting an abundance of greenery wherever it takes our fancy.
In fact, there are some vital things that we all need to be aware of before we take any action to counter the effects of pollution organically.
Adopting a ‘green architecture’ mindset is the only way of minimising the harmful effects on human health and the environment. This is because getting it right requires analysing a number of variables before making any plans. The geographic layout of the area, the direction of air movement, the location of the pollution sources as well as the type of shrubs, hedges and trees that are to be planted are all things that need to be considered.
To get any element wrong is to endanger the effectiveness of the project.
Trees are not necessarily the answer
When we think of air cleaning plants, it tends to be trees that spring to mind.
Yet one study found that hedges are in fact more effective at cleaning the pollutants out of air and can reduce particles and toxins along busy main roads by around a third.
This is because the hedge creates a barrier and a carbon digesting wall at ground level that is able to absorb fumes nearer to source (car exhausts for instance).
Furthermore, some tree varieties can in fact be lethal if planted in cities.
Cedar, eucalyptus and pine are just three examples of trees that omit volatile organic compounds (VOCs) which are harmful to human health when mixed with the particles in urban air pollution.
As well as giving off VOCs, densely planted trees can end up creating a ‘canopy effect’ that prevents any polluted air from escaping and adds to rather than resolves the pollution problem.
Trees for green air
Yet, the right type of tree planted in the right place can undoubtedly be an excellent air purifier and help filter out both carbon dioxide and harmful particulate matter (PM).
The silver birch is one such variety. The leaves are covered in tiny hairs and ridges, which help trap the pollution particles. When it rains, the particles that have come to rest on the leaves are washed off so the cleaning/filtration process can begin again.
Silver birch foliage is also rather sparse, which means the air can easily circulate up through its branches and pollution can escape.
Up to 60% reduction
In fact, the silver birch is capable of removing 40 tonnes of C02 from air in 20 years, according to one study.
Furthermore, BBC research showed that an avenue of silver birch trees planted along a busy urban road was responsible for reducing PMs by up to 60% in the homes of the residents living alongside them.
Three other tree varieties that are believed to be as effective at cleaning air as the silver birch tree are the common ash, the large leaf linden and the Norway maple. Lesser so are hawthorn, hazel, holly, mountain ash and sycamore, which are all described as having a small capacity to improve air quality.
So, although plants can reverse a lot of the harmful pollutants in the air, it is within the interests of our health to make sure we don’t add to the problem by putting the wrong type of plants in the wrong place.
A leafy green hedge flanking your garden’s perimeter with an avenue of birch, linden or ash trees at the bottom could be the answer to creating an attractive, organic boundary in your garden as well a garden oasis of purified air from which to breathe.
If you would like help in creating a garden that will help purify the air and counter the harmful effects of air pollution, please get in touch with Thames Valley Landscapes. We can take on the hard work of designing, digging and planting an effective organic barrier to help clean the air that surrounds your home.