Appendix 6. Odour Buffer Assessment [As Published] · 132007.2399

3    ODOUR ASSESSMENT CRITERIA

The Queensland EPA Guideline on „Odour Impact Assessment from Developments‟
contains a detailed discussion of issues associated with odour response and
assessment. This section briefly describes the basic factors associated with odour
response, known as the FIDOL factors, and then identifies assessment criteria.

3.1 Factors Affecting Odour Response
Analysis of community odour exposure has identified five factors that are important
in determining the potential for annoyance and complaint:

              Frequency (how often odour occurs);

              Intensity (how strong the odours are);

              Duration (how long odour events last);

              Offensiveness (the degree of unpleasantness); and

              Location (is the location „sensitive‟?).

These are together called the FIDOL factors (NZ Ministry for Environment, 1995).
Generally, the greater the frequency, intensity, duration and offensiveness of an
odour the more likely it is to cause annoyance and lead to complaints.


3.2 Quantitative Odour Descriptors
Key elements of quantitative odour criteria that are used for planning purposes are:

                     Concentration

                     Averaging time and

                     Percentile value

Concentration is the odour strength (in odour units) as determined by dynamic
olfactometry.

Averaging times for odour criteria are generally either 1 hour or 3 minutes, or in
the case of NSW the „nose response time‟, taken to be approximately 1 second.
Dispersion models that are used for predicting or simulating odour concentrations
utilise a basic time interval of one hour for individual calculations. For smaller
averaging times, the 1-hour result is converted using a statistical relationship
between concentration and averaging time.

The percentile value refers to the percentage of time (usually over a full year)
during which the actual odour concentration must be within the criterion
concentration.

The shorthand notation incorporating these parameters is written in the form C p,t
where C is the concentration and the subscripts p and t refer to the percentile value
and the averaging time, respectively. For example, C99.5 1-hr refers to the 99.5th
percentile 1-hour average concentration.



1898b Report.doc                                                                        4
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