Trees do a lot more than just produce the air we breathe. We’ve covered some of these services in other stories, but urban trees bring us slightly different benefits, because we often live among them. They can absorb rain, cool their surroundings through shade, and provide space for relaxation. And most importantly, their leaves pick up particles of air pollutants, so that we have not just air, but fresh air . In Southampton, UK, that’s worth £535,000 a year.
Southampton’s urban trees
Southampton has quite a few green spaces. The Southampton Common is home to the largest population of the rare great crested newt, which by the way is a lizard… sort of. Overall, Southampton has a fair amount of urban trees, similar to London or other cities in the UK. They remove pollutants like nitrogen dioxide, sulphur dioxide, and small particulates that can cause shortness of breath, chest pains, and acid rain, especially over time.
Trees do a lot more than just produce the air we breathe.
These health effects cost society money, which means the pollutants cost society money. So the amount removed by the trees tells us how much the fresh air is worth.
Fresh air and other benefits
How do they do this, exactly? It’s actually quite easy: trees’ leaves absorb air pollutants and particles, and then release or use some of them. (warning: 1977 PDF.) There are all sorts of factors that affect how well this works, like how healthy or old the trees are, how big their leaves are (since leaves pick up pollutants, leaf size affects how well they can clean the air), and how many different species there are.
Pollutants cause health effects that cost us money, but trees help to clean them up.
More is better for most of those things, but thick canopies, like on heavily tree-lined streets, can actually trap pollution. So it’s important to check on things like location and the direction of air flow. But either way, urban trees provide lots of benefits for city slickers.