Source: doi: 10.2495/SDP-V11-N4-578-587 ; The Zeppelin observatory is a research station near the village Ny-Ålesund in Svalbard. The facility delivers data to international projects devoted to high data quality monitoring of the background air pollution in the Arctic. An approach for quantifying the influence of local and regional pollution on measurements that may be misinterpreted as long-range transported one, is presented here. The hourly gas and aerosol data measured in Ny-Ålesund and at the Zeppelin station, respectively, have been analysed along with the meteorological data from Ny-Ålesund, Zeppelin station and Longyearbyen (south-east of Ny-Ålesund). Seasonal fluctuation of the average measured values of SO2 and NOx has been observed. Three main wind directions coincided with the peak concentration of SO2 and NOx. The NW-N flow may bring local pollution from ship traffic and diesel power plant as well as biogenic SO2 from the oxidation of DMS. The monthly average number of particles with diameter characteristic for ship plume (50–100 nm), was elevated for the hours when ships have been registered in the local call list. The number concentration of particles with diameter 200 nm, typical for Arctic haze events, and concentration of non-sea salt sulphate rise during springtime. The FLEXTRA-trajectory analysis indicated that most pollution brought by E-SE and SW flows may be of long-range and/or regional origin. Events with these flow directions need to be interpreted with caution.