O•, O[subscript 2] and O[subscript 3] play vital roles in the Earth's atmosphere, regulating ultraviolet radiation from the Sun and being essential for life. However, the oxygen family, O•, O[subscript 2] and O[subscript 3], also provides a source of the HO radical, the atmospheric detergent that removes pollutants from the atmosphere. This article also discusses the decline in oxygen levels that have been observed and the latest data that suggest that the stratospheric ozone hole is recovering.