Improvement of sensory odour intensity scale using 1-butanol reference solutions for environmental odour evaluation

For appropriate evaluation of environmental odours, it is necessary to develop a reliable odour measurement scale. Odour intensity reflects people’s perception of odours and contributes to effective odour management. In this study, Japanese conventional six-point odour intensity scale was reconsidered to ensure equal intervals between odour intensity levels. A new series of six dilution steps of 1-butanol solutions with a concentration of 0, 10, 600, 2600, 9000 and 22500 ppm (vol/vol) was proposed and explanatory labels for odour intensity levels were determined. In addition, polyethylene (PE) bottles were proposed as containers for 1-butanol odour intensity reference solutions for convenience in on-site handling, and the effectiveness of PE bottles was suggested. These results showed that the new odour intensity scale would be applicable to on-site investigations and practically useful for all people related to environmental odour evaluation.