How Urban Trees Help Clean the Air
We often associate trees with shade, wildlife and beautiful green spaces, but they also play an important role in helping us breathe cleaner air. As towns and cities continue to grow, urban trees are becoming increasingly important barriers to air pollution and creating healthier places to live.
Why is air quality important?
Before we look at the role trees play in improving air quality, it's worth understanding why clean air matters in the first place.
Clean air can save lives
Poor air quality has a significant impact on our health. Breathing polluted air over long periods can increase the risk of conditions such as asthma, heart disease and stroke.
Children are particularly vulnerable because their lungs are still developing, and people living in urban areas are often exposed to higher levels of pollution. Recent research found that cleaner air in London was linked to healthier lung development in children, highlighting the importance of tackling pollution where people live, learn and play.
Clean air supports our wellbeing
Growing evidence suggests that poor air quality can also affect our mental health and wellbeing — increasing stress levels and the risk of depression. At the same time, cleaner, greener environments can help create healthier places to live, work and connect with nature.
Trees and green spaces alone are not the answer, but they can form part of a wider approach to creating happier, healthier urban environments.
Clean air affects our economy
Poor air quality doesn't just affect our health. It also has a significant impact on businesses, workers and local economies.
Air pollution is linked to reduced productivity, staff absences and increased pressure on healthcare services. Globally, an estimated 1.2 billion working days are lost each year due to the effects of air pollution, while the wider health damage is estimated to cost $6 trillion annually.
How urban trees help clean the air
Urban trees do much more than make our streets look greener.
Most people know that trees absorb carbon dioxide, but they can also help remove other pollutants from the air. Their leaves, bark and branches can trap tiny particles from traffic and other sources of pollution before we breathe them in — making towns and cities healthier places to live, reducing air pollution.
In fact, London's trees remove an estimated 2,241 tonnes of air pollution every year, including dust, carbon dioxide and other airborne pollutants.
This is one of the reasons urban trees are so valuable. Every tree added to a neighbourhood contributes to a healthier urban environment.
Why does the right tree in the right place matter?
As well as helping to absorb pollutants, trees can act as natural barriers.
When planted strategically, trees and shrubs can help reduce people's exposure to pollution from busy roads by screening against airborne particles and creating a buffer between traffic and the places where people live, work and go to school.
However, planting more trees is only part of the answer.
Research increasingly shows that the greatest benefits come from planting the right trees in the right places. Different species provide different benefits. Some are particularly effective at trapping pollutants, while others are better at cooling streets, supporting pollinators or boosting biodiversity.
This thinking sits behind our Planting for Roadside Air Quality Guide, developed in partnership with Tower Hamlets Council, Dr James Levine and Treeconomics. The guide explores how carefully planned tree planting and green infrastructure can help improve air quality in urban areas and create healthier places for people and wildlife.
Planting for cleaner air in Tower Hamlets
In Tower Hamlets, one of London's least tree-covered boroughs, we've planted more than 14,000 trees since 2019, helping create greener neighbourhoods and bringing the benefits of trees to communities that need them most.
In January 2026, we planted 215m² of hedgerow at Millwall Park in Tower Hamlets, next to a well-used footpath and cycle route. Baseline monitoring showed that NO₂ levels along the route were above World Health Organisation (WHO) recommended standards. By planting hedgerow beside the road, we aim to help screen the path from roadside pollutants, so that in years to come, local people will have a greener route to school, work and the park.
Nearby, at Padstow and Bethlehem House Estate, we saw a similar challenge. The estate playground is used by local children after school, just as rush-hour traffic builds up along the road beside it. Our NO₂ readings at this site were also above WHO recommended levels. In response, we planted 88m² of hedgerow to help screen the playground from roadside pollutants, so that as it grows, children will have a greener, more protected place to play.
Why this work matters
At Trees for Cities, we plant thousands of urban trees each year across the UK. Our work helps urban communities adapt to climate change, improve air quality and deliver benefits for both people and nature.
With more than 84% of people in the UK living in towns and cities, access to cleaner, greener streets matters. The right trees, planted in the right places and cared for over time, help create healthier, happier and more resilient urban communities for generations to come.
Donate to Trees for Cities and together we can create leafy, liveable cities now and for future generations.
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