This technological program aims to get a better view of the Corbel site quality (78 54 N, 12 07 E, Svalbard close to Ny Alesunsd) for atmospheric chemistry. Nox and SO2 samplers are deployed on 16 places on a 4 km2 area around the Station (79°N, Svalbard), protected from snowscooters activity. The influence of Ny Alesund village is also studied. Programme 2004 April 2004 : poles installation and samplers deployment on the 16 stations; analysis will be made by CNR.