Passive diffusion samplers (PDS) composed of a vial with a solution of distilled water and ethylene glycol have an affinity to capture tritium oxide (tritiated water vapour, HTO) from surrounding air through an orifice in a lid. In order to ascertain the effectiveness of such samplers for tracking changes in the HTO air concentrations attributable to variations in tritium emission rates, the Canadian Nuclear Safety Commission (CNSC) measured the HTO concentrations in air for one year on a bi-weekly basis at various distances along four directions from an operating radioluminescent light manufacturing facility. The collected data demonstrate that the PDS are low cost and low maintenance means for reliable monitoring of airborne HTO emissions. The data indicate a rapid decrease of atmospheric HTO concentrations with increasing distance from the facility in all directions. A strong correlation (r=0.89) was found between reported releases of HTO from the facility and the HTO air concentrations observed at the monitoring locations. Distribution of HTO around the facility correlated strongly (r=0.99) with local wind distribution.