Denmark has obligations according to the agreements in the Montreal Protocol, ie. for the monitoring of the ozone layer. This project is a fullfilment of these obligations, and the work is being supported by the Danish Environment Protection Agency (Danish EPA) through a DANCEA funding. Recommandations for the monitoring are updated every 3rd year via the Ozone Research Managers (ORM) Meeting at WMO in Geneva. The most recent meeting was in 2017. The monitoring program was initiated in 2002. The current partnership consists of Latmos (FR), NASA (US) and DMI (DK). Monitoring of the ozone layer and measurement of the UV radiation currently takes place in 2 locations in Greenland: Kangerlussuaq and Ittoqqortoormiit. In Kangerlussuaq the instrumentation consists of a Brewer spectrometer capable of measuring the ozone column and doing UVB scans, a SAOZ spectrometer measuring ozone and NO2, and an Aeronet Sun Photometer (hosted for NASA). In Ittoqqortoormiit the instrumentation consists of an ozone balloon borne sounding station, a SAOZ spectrometer (hosted for Latmos), a GUV 2511 broadband instrument and an Aeronet Sun Photometer (hosted for NASA). Retrieved data is uploaded to international databases (WOUDC, NDACC & NILU). Retrieved data is used to correct satellite measurements and to monitor the state of the ozone layer.