A proposed development that will change the concentration of pollutants in the atmosphere, or alter the weather and climate, may result in effects on people, plants, animals, materials and buildings (Canter 1996, Colls 1997, Elsom 1992, Ortolano 1997, Turco 2002). These effects can occur at the local, regional or even global scale. Major developments, such as power stations, oil refineries, waste incinerators, chemical processing plants and roads, pose obvious potential pollution problems. In addition, even developments that emit little or no pollutants when completed and operating can create a local dust nuisance during the earth-moving and materials-handling operations of the construction stage, especially during dry weather conditions. Once completed, developments may give rise to additional vehicle emissions as people travel to them (e.g. edgeof-town shopping and leisure complexes). New roads will directly result in vehicle emissions, and some developments may cause emissions at other remote locations such as power stations.