Surface ozone is measured at 70 ¿N and 78 ¿N with analysers having response time of 1 and 20 sec, and characteristic ozone depletions due to polluted air are revealed. Using the rapid instrumental time response, significant variations are found to occur within a few seconds. It is hard to find any ozone enhancements due to polluted air, and local ozone production seems to have minor importance. Therefore no significantly enhanced ozone levels due to local and long-range transported car exhaust are likely to occur at high latitudes. Additional depletions due to dry and wet depositions are probably occurring. ¿ American Geophysical Union 1996