Trees for the 21st Century Imagine . . . The pollution from one car can be absorbed in a year by 400 growing trees. An average tree exhales enough oxygen in a day to keep a family of four breathing. Trees remove dust and pollution from the air. Water Quality and Quantity From their leaves to their roots, trees protect water quality.
Tree roots soak up storm water, hold soil in place on steep slopes, and trap pollutants.
Trees capture rainfall and help recharge drinking water sources. Runoff from forested areas is 17 percent less than that from developed areas. Economics Three trees planted in the right place around buildings can cut air-conditioning costs up to 50 percent. Trees also may be planted to block the wind and lower heating costs. Trees increase the value of property.