ABSTRACT Particulate sulphate (pSO42–) is an atmospheric pollutant known to affect human/environmental health and global radiative-forcing. The Rio Tinto (RT) aluminium smelting facility in Kitimat, British Columbia, is the primary source of sulphur dioxide (SO2) emissions to the surrounding Kitimat Valley, a relatively isolated and unpolluted region. A network of active two-stage filter-packs and passive-diffusive samplers was established between June 2017 to October 2018 with the objective to evaluate the spatiotemporal variation and relative contribution of pSO42– to total anthropogenic atmospheric oxidized sulphur (SOx = SO2 + pSO42–). Average pSO42– across all sites (n = 9) was 0.41 µg m–3 (24–48 hour exposures) and ranged from 0.03 to 2.03 µg m–3. In contrast, average filter-pack SO2 ranged from 0.11 to 8.9 µg m–3 (during the same exposure periods). The filter-pack pSO42–/SOx concentration ratio (Fs) increased downwind of the smelter, indicating that the relative concentration of pSO42– increased with distance from the smelter. Furthermore, the increasing pSO42–/vanadium (V) ratio (used as a tracer of smelter emissions) relative to distance confirmed particulate formation was occurring within the emission plume during the sampling period. Irrespective of in-plume aerosol formation, pSO42– contributed a relatively minor fraction of total atmospheric SOx within the emission plume (field campaign averages Fs 1.0 µg S m–3).