• Assessment of odour annoyance in chemical emergency management

      Ruijten MWMM; Doorn R van; Harreveld AP van; SIR (CrisisTox ConsultMunicipal Health Service Rotterdam (GGD)OdourNet BV, 2009-06-11)
      In chemical emergencies the exposed community is likely to interpret the presence of an unusual odour not common to the normal 'odour landscape' as a potential health risk. This report describes a methodology for assessing the airborne concentration level at which the exposed community is likely to become aware of the presence of a chemical by detecting its odour, which in turn may require communicative emergency response activities, even in the absence of toxicological health risks. The presented methodology will help emergency response organizations to improve the understanding of odour driven public concerns in chemical emergencies, and improve their ability to assess if and which type of response is adequate. The methodology builds on consensus reached within the Acute Exposure Guideline Levels (AEGL) program that an airborne concentration producing a distinct odour perception in more than half of an accidentally exposed, distracted population would qualify as significant odour awareness. This concentration is designated as 'Level of distinct Odour Awareness (LOA)'. The LOA is determined in three steps: 1. Select an appropriate odour threshold, for instance from one of the suggested sources. 2. Derive a distinct odour level based on the Weber-Fechner equation. 3. Adjust for field circumstances such as age, head cold and the usual exposure pattern. The LOA must be developed on a chemical-by-chemical basis. The availability of high quality chemical specific information for steps 1 and 2 is a major hurdle, which has been partly overcome by introducing default values.