Air Pollution is a global crisis, with road traffic being the major contributor to the growing problem in cities all over the world. Nitrogen dioxide (NO₂) produced by car engines and fine particulate matter (PMs), which cars create through the wear and tear of tyres and the road surface are of most concern.
London has the highest levels of nitrogen dioxide (NO2) pollution of any capital city in Europe and there are concentrations of dangerous airborne particles (PM10) which breach legal limits in several parts of the city (according to https://cleanair.london/). Poor air quality has a significant impact on the health of London residents. The Mayor published a study in 2010 estimating 4,267 premature deaths in London in 2008 were attributable to long term exposure to fine particles (PM2.5).
The Great West Road (A4) with its six lanes of constant traffic is estimated to carry 120,000 vehicles a day, creating an enormous amount of air pollution, regularly breaching the targets set by the WHO.
The Great West Road is estimated to carry 120,000 vehicles a day.
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 last word on air pollution on the Great West Road, but it will help, as it will also for noise pollution.
The project will measure its success in mitigating air pollution, by also providing air monitoring sensors along the road to calculate the air quality before and after the planting takes effect.