Every 16 September, World Ozone Day reminds us of the need to protect the ozone – a thin, protective layer of gas that absorbs most of the sun's harmful ultraviolet light. In doing so, the ozone layer helps protect humans from skin cancer and cataracts, and shields plants, crops and ecosystems from damage. The year 2020 marks more than three decades of global efforts to conserve and restore the ozone – which have paid off.