Compared to bear ground, cement or synthetic turf, grass will reduce the surrounding surface temperature by 15 C and a neighbourhood of eight average lawns has the cooling affect of 70 tonnes or air conditioning. (Twice the cooling affect provided by the air conditioners of those same eight homes! ) Lawn is a natural filter. Grass absorbs CO2, and other hydrocarbons and a range of other poisonous gasses, converting them to oxygen. In fact 25 meters of lawn will produce sufficient oxygen to generate a quality of air suitable for a family of four! It is also estimated that grass traps twelve million tons of dust annually (on a global scale), filtering the pollutants as the dust is washed back to the soil during periods of rainfall. The benefit that lawn can make to the environment is the capacity to cleanse our water supply. Rainfall washes and carries pollutants from the atmosphere through the root system of your lawn. A 100 square meters of lawn can develop a maze of 500 million kilometres of roots which trap pollutants before they reach and pollute our ground water supply. With the help of soil microbes, grass converts most these pollutants into harmless organic compounds that build up our soils to support more life.