Odors are a continuing source of concern to some residents in the Regional Municipality of Wood Buffalo that includes the Athabasca Oil Sands Region (AOSR). Sulfur dioxide (SO 2), fugitive volatile organic compounds (VOCs), and a variety of sulfur-inorganic and -organic compounds, which in total are called total reduced sulfur (TRS), can be a source of this odor. The organic fraction of TRS is, as a general class, the most odiferous. To help understand this issue, the Wood Buffalo Environmental Association (WBEA) of Alberta instituted a program for the dual measurement of these compounds by pneumatic focusing gas chromatography (PFGC). The PFGC, normally equipped with a flame ionization detector (FID) for measurement of VOCs, was fitted with a parallel pulsed flame photometric detector (PFPD), and was deployed in 2009 at a WBEA ambient air monitoring station (AMS-2) near emission sources in the area. The instrument successfully measured a variety of hydrocarbon and sulfur compounds at the ppb level. After 2009, Oil Sands processing procedures were apparently modified in the AOSR, with a resultant 10- to 100-fold drop in gaseous sulfur compound levels, and a drop in public odor complaints. At that time, the PFGC was moved to the WBEA Bertha Ganter-Fort McKay air monitoring station (AMS-1) in the First Nation community of Ft. McKay. Here, in spite of greatly reduced sulfur compound levels, odor complaints were still received. The concentrations of sulfur compounds at this new location, however, were below the detection limit of the PFPD. To address this challenge, the PFPD was replaced with the more sensitive sulfur chemiluminescence detector (SCD). As documented in this chapter, the newly designed system is now routinely identifying and quantifying individual sulfur compound concentrations well below 100 parts per trillion (ppt). Such greatly enhanced sensitivity is necessary to address odors that still persist in the AOSR, so that odor types can be identified and communicated to stakeholders.