The importance of having the city "populated" also trees not only measured through the beneficial effects on health, but also in economic terms.
So the British newspaper "The Guardian" has dedicated a survey of the economic value of green in urban areas.
The positive consequences on people's pockets (and on the public purse) depend on the fact that the trees have the ability to lower the temperatures in densely populated areas: has been calculated, as reported by the British newspaper, which planted areas near the buildings can be reduced the use of air conditioners also of 30% (the data come from the UN urban forestry office), while a large tree is able to absorb 150 kg of carbon dioxide per year, doing so as a filter for a number of polluting substances otherwise dispersed in the air.
In New York, the parks department has estimated at about $ 120 million per year savings on public coffers caused by trees, including improved air quality, energy savings, costs to prevent flooding due to heavy rainfall.