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Air Pollution mitigation

The Great West Road (A4) with its six lanes of constant traffic, estimated to carry 120,000 vehicles a day, creates an enormous amount of air pollution, regularly breaching the targets set by the WHO. Nitrogen dioxide (NO₂) produced by car engines and fine particulate matter 2.5 (PM2.5), which cars also create as dust through the wear and tear of tyres and the road surface are of most concern.

Communities near roads such as these suffer most from the effects of these airborne pollutants, exposure to which increases the risk of cardiac, cancer and chronic respiratory diseases.

There are 8 schools, 6 nurseries, 6 parks as well many residential houses and offices along both sides of the A4 where the planting will happen.

Greenery on the sides of roads can provide some mitigation, either acting as a physical barrier to contain the pollution on the road, or via deposition when the pollution sticks to the surface of a leaf and is removed from the air, or via dispersion, transporting pollutants with the wind away from the source and where they get diluted with cleaner surrounding air.

The Great West Hedge is not the solution to the air pollution on the Great West Road, but it will help, as it will also for noise pollution.

The project will also provide air monitoring sensors along the road to better measure the air quality on either side of the road and the improvements after the planting takes effect.

The project will help reduce air and noise pollution from the A4.

Bio-diversity enhancement

The loss of biodiversity poses as great a risk to humanity as climate change


The built environment is a major contributor to the breakdown of biodiversity.

The proposed combination of planted trees, hedges, wildflowers and other planting will not only provide a barrier against air pollution, but also a corridor for wildlife and pollinators; and a solution to help mitigate the effects of climate change.

Increased biodiversity will help sustain the ecological balance that urban centres often lack, reinstating local and unexpected plants, as well as encouraging insects, pollinators, butterflies and birds.

Nature can thrive along the Great West Road.

Benefits to the community

The A4 is a moat that cuts off the residents of Hammersmith & Fulham and Hounslow to the jewel that sits in both boroughs, the River Thames. Due to its noise, dirty air and dangerous traffic, residents cannot access the parks and riverside walks alongside the Thames as easily as they should. It is time the road was reclaimed for local residents, not simply acting as a thoroughfare for people trying to reach central London.

The road has wide pavements for both pedestrians and cyclists, yet few users, something that more greenery and a more pleasant environment would encourage.

More greenery will help mental health, as well as physical well-being, with many studies showing that access to nature improves many mental health issues and can reduce stress, increase happiness and reduce negative emotions, promote positive social interactions and even help generate a sense of meaning to life.