Passive samplers are subject to a myriad of sources of uncertainty, which affect their precision and accuracy. To investigate this uncertainty, an evaluation of passive sampler data for SO2, NO2, O3, and H2S was carried out in the Lakeland Industry & Community Association in east- central Alberta from 2009 – 2011. The results of this study indicate that while passive sampler data followed the same general trend as continuous monitoring data, passive sampler data were often statistically different which strongly indicates they were not always accurate. Passive samplers are further limited by only providing a time weighted average of pollutant concentrations over the sampling period, which prevents determination of when or where a pollutant has exceeded regulatory limits. While passive samplers are useful in monitoring general changes in ambient air quality at low concentrations, this work strongly suggests that passive sampler data should not be used for regulatory monitoring.