Air conditioning eventually reach the upper atmosphere. Once the refrigerant reaches the stratosphere, UV radiation from the Sun homolytically cleaves the chlorine-carbon bond, yielding a chlorine radical. These chlorine radicals catalyze the breakdown of ozone into diatomic oxygen, depleting the ozone layer that shields the Earth's surface from strong UV radiation. Each chlorine radical remains active as a catalyst until it binds with another radical, forming a stable molecule and quenching the chain reaction. Prior to 1994, most automotive air conditioning systems used R-12 as a refrigerant. It was replaced with R-134a refrigerant, which has no ozone depletion potential. Old R-12 systems
UV filter nm), UVB (290-320 nm) and UVC (200-280 nm ). Ultraviolet absorbing compounds are the active ingredients of sunscreen products and other personal care products (e.g. lipsticks, shampoos, hair sprays, body washes, toilet soaps, and insect repellents). Chemical filters are generally used in combination in order to get sufficient protection against UV. They protect humans from the serious effects of UV radiation by absorbing, reflecting or scattering it. The reflection and scattering effecst are done by physical UV filters which are inorganic UV filters such as titaniumdioxide (TiO) and zinc oxide (ZnO). Absorption is accomplished by organic UV filters which are