Comparison of sensory odour intensity scales for inexperienced assessors

Odours discharged from various human activities may cause severe damage to local residents. For appropriate evaluation of environmental odours, it is necessary to develop a reliable odour measurement scale. Since environmental odours consist of many different odorous compounds, comprehensive evaluation of odours using human sense of smell as well as instrumental analysis of individual chemicals is indispensable. Odour intensity reflects people’s perception of odours and contributes to effective odour management. For ordinary environmental odour monitoring by neighborhood and routine odour management at emission sources, reliable and user-friendly sensory odour intensity scale even for inexperienced assessors is desired. In this study, four odour intensity scales, including conventional six-point scale, 1-butanol reference scale, line segment scale and metronome scale, were applied to odour intensity measurement of 1-butanol and ethyl acetate solutions by inexperienced assessors. Trueness and precision of measurement results were evaluated, and advantages and disadvantages of each scale were discussed.