The city of Los Angeles has launched a tree planting program near houses and other living areas. Each home can have up to seven trees (to be chosen among thirty species available) delivered to them for free. The city then offers the people lessons to teach them how to maintain the trees.
There are several advantages to this : on the one hand, the shade of these trees makes houses cooler naturally which limits energy expenditure and air pollution caused by air conditioning. The trees also improve air quality in town and slow down soil erosion.