Ozone–oxygen cycle Ozone–oxygen cycle The ozone–oxygen cycle is the process by which ozone is continually regenerated in Earth's stratosphere, converting ultraviolet radiation (UV) into heat. In 1930 Sydney Chapman resolved the chemistry involved. The process is commonly called the Chapman cycle by atmospheric scientists. Most of the ozone production occurs in the tropical upper stratosphere and mesosphere. The total mass of ozone produced per day over the globe is about 400 million metric tons. The global mass of ozone is relatively constant at about 3 billion metric tons, meaning the Sun produces about 12% of the ozone layer each day. And if
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