Polution in the city still is hazardous. Especially nitrogen dioxide (NO2) and microscopic particulate matter (PM) exceed those levels and can be a threat to human health.
We already do quite a big deal to decrease polution from traffic. Special filters can get most of the microscopic dust out of the exhaust. But a lot of these measure don’t extend as far as to look into the depositional schemes of polution.
This study suggests that a greener city would actually reduce the polution by NO2 by 40 percent and PM by 60 percent. This is far more than initially thought by other studies (<5%).
They had a look at grass, climbing ivy and also trees. Important on the tree side. They help but you have to be careful not to “trap” the polutants under a rich green canopy.
How come this studies findings are that much bigger than precious ones?
They claim that previous studies did not take into account that air gets trapped in “urban canyons” and starts to circulate. This “enhanced residence time” is especially important when looking into plants as filters since they need their time to actually pick up the pollutants.
Maybe you would like to have a look into greening projects in your part of the world?
There are quite a few.
Britain in Bloom http://amplt.de/l6
Tree City USA http://amplt.de/l7
Just have a look. And wouldn’t a greener city also be something nice for the eye?
Read the article: http://amplt.de/l5
Image by Alfred Hutter