Odour Regulation in Germany – an improved system including odour intensity, hedonic tone and odour annoyance

For odour regulation in Germany the Guideline on Odour in ambient Air GOAA has been in use for many years. The main parameter the odour regulation authority has to take into account is the odour frequency expressed as odour hours per year. In the Guideline limit values are given for the maximum odour frequency per year. These limit values are based on investigations in the field in which significant relationships between odour impact and odour annoyance were found. In these investigations odour intensity did not yield a better description of the annoyance degree of residents. The hedonic tone was not mentioned. In a new research project the influence of odour intensity and hedonic tone in addition to odour frequency has been assessed. As a consequence of this investigation there is no need to modify the fundamental system of data acquisition, analysis and evaluation of the GOAA but the results show that in some cases (pleasant odours) it is necessary to include hedonic tone. Therefore hedonic tone in the case of pleasant odours and a reliable and valid method to evaluate hedonic tone in the field is included in the GOAA.