Trees are commonly known to act as natural filters that maintain clean air and reduce CO2 levels. It is less well known that trees can cool cities down as well! They do so by providing shade and by allowing water vapor to emit from their leaves, cooling the air around them!
Parks don't only improve the air, but the water as well. Parks absorb water from rainfall which helps prevent flooding. This absorption also allows the greenery to naturally filter the water, making it safter for residents to drink!
City parks encourage increased physical activity among residents as it is much more pleasant to walk through a park full of birds chirping, water flowing, and children playing than it is to walk down a crowded and noisy city street. The increased physical activity that parks bring improves the physical health of city dwellers, decreases medical costs for both individuals and the city, and relieves stress put on overcrowded medical facilities!
City parks have been found to reduce crime within cities. This is done through 2 things that parks bring. Firstly, parks serve as a central gathering place. Crime is most common in isolated areas, so by bringing the community together in a social hotspot, there are fewer opportunities for criminals to strike. City parks also reduce crime by filling vacant urban lots that can be hotspots for criminal activity.
Information from City Parks Alliance and the NRPA