Can a stench be measured?

Judging odours at first seems a subjective matter. One person finds a smell bearable, another finds it disturbing. Complaints from residents are often emotionally charged, which makes professional dialogue even harder.

But there is one important fact: the extent of an odour impact is not a matter of opinion.

The perception of odour is subjective, but the extent of the odour impact can be measured objectively.

Today dynamic olfactometry is available, which can determine odour concentration and the level of odour emission in a standardised way, and shows precisely to what extent a site burdens its surroundings.

This is not merely a tool often used by the authorities for odour measurement, but a strategic decision-support method. Measurement makes it possible to:

• identify the main odour sources,

• distinguish between point and diffuse odour emissions,

• rank the points for intervention,

• prevent conflicts caused by unpleasant odours from escalating.

  
  

Measuring the odour load is important not only for compliance with the authorities, but also because it gives the site manager an accurate picture of the real situation, so that decisions do not have to be made afterwards, under pressure.

Why is "smelling it" not enough?

An odour that people at the site are used to is not necessarily acceptable to the surrounding area. This difference in perception causes most conflicts, regardless of how long the site has been operating.

Site workers often do not notice the problem. Because they get used to odours (adaptation), judgement inside the site is distorted. Meanwhile, for people living nearby, the same odour emission can be intense and disturbing.

This difference in perception is a serious source of conflict. If the site manager relies solely on internal experience, the risk can easily be underestimated.

The role of dynamic olfactometry

Dynamic olfactometry is a standardised measurement method that determines odour concentration in odour units/m³. The essence of the method:

• sampling at the emission points,

• use of dilution series,

• determination of the detection threshold by a trained panel.

The result is a numerical value that can be used to prepare documentation for the authorities, to support investment decisions and to resolve disputes objectively.

Point or diffuse odour source?

Odour emission is not always concentrated, and we distinguish two basic types:

• Point odour sources, which can be vents, stacks and extractors.

• Diffuse odour sources, which can be manure storage, open surfaces and odours from field spreading.

Choosing the right solution depends on which type dominates.

Measurement as a strategic tool

Many people only order a measurement once environmental proceedings have already started. Yet the real value of measurement lies in prevention.

Objective data make it possible to:

• identify emission peaks,

• model meteorological effects,

• prepare risk maps,

• prioritise investments.

In this way odour becomes not a reputational risk but a manageable operating parameter.

Knowledge and preparedness

Odour management is not an "extra service" but a professional competence. Sharing experience and practical examples on the subject is especially important, as every site has different characteristics.

Professional forums, chamber presentations and exchanges of experience help site managers deal with odour problems through conscious decisions rather than under pressure.

Experience shows that the sites able to operate with minimal risk are those that treat odour not as firefighting but as an operational matter. There, the survey, the identification of odour sources and the selection of suitable solutions – designed for point or diffuse sources – take place before any complaints arise.