Odour is a significant challenge in sectors such as waste management, food processing, biogas production, slaughterhouses, rendering plants, and wastewater treatment. These industries generate strong and persistent odours. If not properly managed, these odours can affect employees, nearby communities, and the overall perception of the industry, leading to complaints, regulatory action, and reputational damage. Unlike specific gases or particulate matter, which can be measured with straightforward instruments, odour is more complex because it depends on both chemical composition and human perception. This makes odour measurement a unique field where cutting-edge digital sensors are seamlessly integrated with traditional bag-sampling techniques, which are still analysed manually by trained panellists in specialized odour laboratories.
Samples are collected in the field and transported to the odour laboratory or alternatively a mobile odour laboratory is used for on site direct analysis. Sample collection needs to be done with care, monitoring temperature, humidity and contact of gases such as ozone that may during transport. According to the EN 13725 standard, odour samples must typically be analysed within 30 hours of collection, but it is recommended to analyse them within 6 to 12 hours for the most accurate results.
Once in the laboratory, odour panellists—typically a group of four—are required to assess the sample. These panellists are carefully selected through sensory testing to ensure their odour perception meets specific standards, and they undergo training to follow a standardized evaluation process.
Image: https://silsoeodours.com/
Practically, the way the odour sampling works, is that the equipment dilutes the collected samples with odourless air in steps, less and less until the panelists sense an odour. When 2 out of 4 panellists sense the odour, the odour value has been determined. This concentration is expressed in odour units per cubic meter (ouE/m³). The higher the odour concentration, the stronger the smell.
The panellists also assess the hedonic tone of the odour, rating its pleasantness or unpleasantness on a scale typically ranging from -4 (very unpleasant) to +4 (very pleasant). This evaluation helps quantify the odour’s impact beyond just its intensity, providing insight into how offensive or tolerable it is perceived to be.
This method follows the EN 13725 standard, which defines how odour concentration should be determined.
Feel free to contact us if you have any questions or are looking for a partner to carry out an odour measurement near you. We are in contact with most of the experienced operators in the field.
