Ozone is an elemental molecule with formula O3. An explosive, pale blue gas (b.p. 112C) that has a characteristic, pungent odour, it is continuously produced in the upper atmosphere by the action of solar ultraviolet radiation on atmospheric oxygen. It is an antimicrobial agent used in the production of bottled water, as well as in the treatment of meat, poultry and other foodstuffs. It has a role as a mutagen, a tracer, an antiseptic drug, a disinfectant, an electrophilic reagent, an oxidising agent and a member of greenhouse gas. It is a gas molecular entity, an elemental molecule, a member of reactive oxygen species and a triatomic oxygen.