Stratosphere around at midlatitudes, and at about at the poles. Temperatures range from an average of near the tropopause to an average of near the mesosphere. Stratospheric temperatures also vary within the stratosphere as the seasons change, reaching particularly low temperatures in the polar night (winter). Winds in the stratosphere can far exceed those in the troposphere, reaching near in the Southern polar vortex. The mechanism describing the formation of the ozone layer was described by British mathematician Sydney Chapman in 1930. Molecular oxygen absorbs high energy sunlight in the UV-C region, at wavelengths shorter than about 240 nm. Radicals produced
UV filter to sun irradiation, while swimming-pool water is required to be disinfected by chlorination, bromination, ozonation, or UV-irradiation. UV filters can undergo degradation and transformation to more toxic products. For example, Avobenzone undergoes transformation in the presence of chlorinated disinfection products and UV radiation to substituted chlorinated phenols and acetophenones, which are known for their toxicity. Some organic UV filters under UV radiation can generate reactive Oxygen Species (ROS) (OH, HO) (e.g. BP-3, octocrylene (OCR), OMC, phenylbenzimidazole sulphonic acid (PBS), PABA, etc.).The levels of HO in waters of Mediterranean beach reached 270 nM/day as a result of Sunscreens. HO as an