Pierre River Mine Project

HEALTH AENV SIRS 79 – 89
Section 14.1
• The maximum three-minute peak air concentrations were predicted for the
cabin residents, Aboriginal residents and community residents in the area.
• The three-minute peak air concentrations were compared with the
corresponding odour threshold for each assessment case (i.e., Base Case,
Application Case and Planned Development Case).
As the three-minute peak air concentrations were derived from the highest
predicted one-hour ground-level air concentrations, the COPC concentrations
that might be encountered under most circumstances may be exaggerated. This
would result in conservative odour estimates.
Determining the Threshold of Odour
Critical to determining the likelihood of the project’s contribution to noticeable
odours is the need to understand the intrinsic odourous properties of the various
chemicals emitted, including their odour thresholds. The odour threshold refers to
the lowest concentration of a chemical that can be detected by smell following
presentation of the chemical in a clean, controlled environment, without
influence of any outside odours (Ruth 1986).
Odour thresholds are typically determined in clinical setting-type studies. A
panel of subjects is presented with a series of concentrations of the same
chemical in air or water and asked to record at what concentration the odour is
first detected. These studies are difficult to compare as they often differ in sample
presentation, panel selection, purity of the chemical used and data interpretation.
Further, the definition of an odour threshold can vary across studies. In some
cases, the odour threshold is the point at which an odour was detected and in
other cases, the odour threshold is the point at which the odour was recognized.
As a result, a wide variation in odour thresholds is reported in the scientific
literature for most chemicals, including the COPCs associated with the project.
For some chemicals, odour can act as a safeguard against adverse health effects.
Under these circumstances, the odour threshold is lower than the concentration
determined to produce toxicity. Odour may not serve as a warning against
adverse health effects if the odour threshold is much higher than the
concentration required to produce toxicity. Therefore, the presence of an odour
might or might not serve as a warning. Health Canada, however, considers any
detectable odour to have the potential to adversely affect human health. For
instance, the presence of a strong odour could potentially lead to increased stress
in an individual.
For the odour threshold values assumed in the assessment, see Table
AENV 82-2. In order to maintain consistency with the original odour assessment
(see EIA, Volume 3, Section 3.4.7), the odour threshold values provided for the
total reduced sulphur compounds and volatile organic compounds in Table
3.4-26 and Table 3.4-27, respectively, of the EIA were used in the alternate
approach (see Table AENV 82-2). For the chemical groups, odour threshold
values were determined by calculating the geometric mean of available odour
thresholds in the scientific literature (AIHA 1997; Amoore and Hautala 1983;
14-6 Shell Canada Limited April 2010
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