The Odour Unit is the exclusive provider of odour testing services to all three alumina refining companies operating in Australia. These are Alcoa World Alumina (3 refineries in Western Australia), Queensland Alumina Limited (the world's largest refinery in Queensland), and Worsely Alumina Proprietary Limited (one refinery in WA).

At four of the above five refineries TOU has carried out comprehensive odour emission audits, in which all major odour emission sources were quantified, and a total plant emission inventory was completed. In each case, the project was serviced by TOU's mobile olfactometry laboratory - a full-service facility designed to be located near the plant under study. This capability to test odour samples on the day of sampling results in optimum responsiveness to the client and improved accuracy of testing results. Odour assessors are sourced locally and fully trained before participating in testing sessions. All testing was carried out to the Australian Standard AS 4323.3:2001 (equivalent to the CEN standard).

The sampling of alumina refining emissions presented major difficulties to the TOU field teams, due to the high steam content of the emissions (at times saturated). The majority of samples required pre-dilution in order to prevent condensation in the sampling bags. The SUPADILUTA 400 syringe dilution device is now used for this purpose.

In mid-2001 TOU commenced the testing of selected refinery process samples for Odour Intensity, using the VDI 3882 method. This testing has shown a clear differentiation between the odour intensity/concentration relationship for different refinery odour sources. This intensity testing data is now being used in developing an odour impact reduction strategy for at least one of the five refineries.