The odour laboratory is accredited for sampling, measuring and analysing odour emissions from industry, plants, restaurants and other odour emitting companies.
The odour laboratory consists of the following:
- Instrument park for sampling, measuring and analysing odour samples
- Olfactometer to assess the odour strength of the odour samples
- A panel of trained odour panellists
- A workshop for the production of odour bags
The odour laboratory’s measurements and analyses are most often carried out as:
- documentation of compliance with limits for airborne odour for authorities, e.g. in relation to the company's environmental approval or the Danish Environmental Protection Act
- quality assurance of effects when setting up filters to reduce airborne odour, e.g. biofilter, carbon filter, odour washer, etc.
In addition, we carry out a number of customised odour analyses, e.g. the smell of different types of sludge from sewage systems or odour of e.g. packaging or other products with residual odour from manufacturing.
Learn more about odour measurement
How are odours measured?
In contrast to most chemical pollution, odours can be registered immediately, and therefore also often lead to complaints when companies emit odours. Irrespective of whether the odour is pleasant or unpleasant, it can be experienced as nuisance by neighbours.
Odours are measured by collecting air from the source, e.g. a stack, in a bag. This air is analysed within 30 hours in an olfactometer.
The analysis is performed by an odour panel comprising a minimum of four persons in our own odour laboratory. The panellists sniff to samples which are diluted less and less, until the panellists can perceive weak odour. The degree of dilution is a measure of the odour content in the bag. The panellists’ description of the odour is noted – e.g. rotten, chemical or sweet.
How odour samples are collected and analysed is described in a European standard, EN 13.725.
How are odour analyses conducted?
We use a TO8 olfactometer from Olfasense.
The sample bag with the odour sample is mounted on the tube in the lower right corner, and by using clean air, the air in the bag is diluted before presenting it to the odour judges (panellists).
The olfactometer dilutes the samples using compressed air and runs an automatic series of varying dilutions. Four panellists are used in the analysis of the air and they are exposed to the series of varying dilutions and mark once they can smell the sample.
At first, it is diluted so much that no one can smell anything, and after that the smell is gradually made stronger. When a panellist can smell something at e.g. 2,000 times the dilution, a button is pushed (bottom centre of the image). Once each panellist has detected the odour twice, a mean value can be calculated for the sample.
Results are given in odour unit/cubic metre (o.u./m³).
How do we select odour panellists?
We select odour panellists from ordinary people who are tested against the reference substance n-butanol.
The panellists’ odour threshold for this substance must be within the limits defined by the standard for odour analysis. If they are within the limits, such individuals are suitable as panellists and called for odour tests.