Those who overlooked the trees recovered faster and required less pain-killing drugs than those who overlooked the brick wall. In another study, prisoners in cells with treed views were found to use prison health-care facilities less often than those in cells without views. City streets, buildings and parking lots affect the urban climate by absorbing solar radiation and disrupting the natural water cycle. As a result, cities tend to be 3-5 degrees warmer than the surrounding countryside. Urban trees ameliorate this effect by shading streets and buildings and by facilitating transpiration of ground water through their leaves.
Trees also reduce heat loss in winter.
Strategically planted conifers can buffer a building from chilly winter winds, and create a dead air space to prevent heat loss. Fuel savings of 20 per cent or more can be realized. The urban forest removes pollutants and other particulates from our air. Each city tree removes about six kilograms of carbon dioxide from the atmosphere each year. Every tree planted contributes to the purification of the air we breathe every day.