Particle samples were collected by aircraft in the vicinity of Barrow, Alaska, the North Pole, and over the North Atlantic north of Bodo, Norway, during March and April, 1983 as part of the Atmospheric Gas and Aerosol Sampling Program. The sulfate concentrations and aerosol acidities from each of the regions were similar. The average sulfate concentration was 3.2¿1.3 &mgr;g m-3. The aerosol acidity was equivalent to 40¿13% of the sulfate.