Recently, a number of studies have called into question the assumed benefits of too many trees in densely developed urban areas. The research suggests that trees may be responsible for trapping harmful pollutants by obstructing avenues that pollutants would otherwise be able to escape through. As mayors and city leaders consider how to address climate change, and weigh their options, knowing the facts about the effects of trees in urban environments is critical.
In spite of these recent studies, there remains strong evidence that the benefits of trees in urban spaces are a net positive. Their ability to absorb greenhouse gasses and trap toxic pollutants makes them efficient tools for improving air quality. Furthermore, trees simply do not pollute. Mayors and urban planners concerned with pollutant levels and sources should focus their efforts on decreasing traffic, investing in mass-transit systems, and improving access to bike-share programs and cycling lanes.
Research into climate solutions provides valuable resources for city officials. However, misidentifying trees as an environmental problem ignores the fact that real solutions to pollution should address the source. Trees make cities beautiful, clean the air, and provide residents with communities that they can be proud of. Mayors and municipal officials should encourage and increase green spaces and tree canopy in their cities—thereby advancing climate solutions, and improving their community. Find out more about how to take action on climate in your city by visiting Path to Positive Communities.
It may sound like a no-brainer to say that trees improve air quality. After all, we know that trees absorb the greenhouse gas carbon dioxide (CO₂), and that their leaves can trap the toxic pollutants nitrogen dioxide (NO₂), ozone, and harmful microscopic particles produced by diesel vehicles, cooking and wood burning.
Yet some recent studies have suggested that trees may in fact worsen urban air quality by trapping pollutants at street level. A closer look at the evidence – and how it was collected – reveals the root of this dispute, and can help us come to a more nuanced understanding of the impacts of trees on our urban environment.
First things first; it is not trees that pollute the air of cities in the developed world. As car manufacturers are all too guiltily aware, it is mainly road vehicles that cause pollution. And their impacts are compounded by the choices we make about how and what we drive.
Stay connected and get updates from Path to Positive.Subscribe