All forms of exterior lighting can, if badly angled, cause two broad types of problem, namely light pollution and light nuisance. Light pollution can be defined as every form of artificial light which shines outside the areas it is intended to illuminate, including light which is directed above the horizontal into the night sky, creating the skyglow which has erased the stars over both urban and rural areas during the last half-century. CPRE figures showed that light pollution increased nationally by 24% between 1993 and 2000 (see the CPRE maps). Bad lighting can also cause glare or other nuisance, for example by shining into bedroom windows. It is this second avenue of nuisance that is legislated for under the new Act. It must be noted that light nuisance is often referred to as "light trespass" in non-legal materials. Of course the distinction between nuisance and trespass is that trespass, in law, requires an intentional physical intrusion, and light has not been tested under the law of trespass.