Odor Emission Rate Calculator
Combine an odour concentration with a source’s air flow to get its Odour Emission Rate in ouE/s — the source term a dispersion model needs.
Odour emission rate
The Odour Emission Rate is the odour concentration multiplied by the volumetric flow leaving the source, OER = Cod × Q. Flow is converted to m³/s first, so the result is in ouE/s — the input a dispersion model needs.
From concentration to emission
Odour concentration tells you how strong the air is at the source; emission rate tells you how much odour is actually leaving it. The bridge between them is the volumetric flow. A vent pushing a modest concentration through a large fan can emit far more odour than a pungent but nearly still source.
Getting the flow unit right matters as much as the concentration: a factor-of-3600 error hides in the difference between per-second and per-hour. This tool converts flow to m³/s first so the emission rate is always in the ouE/s a model expects.
Frequently Asked Questions
What is the Odour Emission Rate (OER)?
The OER is how many odour units a source releases per unit time, in ouE/s. It is the product of the odour concentration leaving the source (ouE/m³) and the volumetric flow of that air (m³/s): OER = concentration × flow.
Why is emission rate more useful than concentration alone?
Two sources can share the same odour concentration yet affect neighbours very differently if one moves far more air. The emission rate captures both strength and volume, which is why dispersion models take an OER — not a bare concentration — as their source term.
Which flow unit should I enter?
Use whatever your stack or duct data are in — cubic metres per second, per minute, or per hour. The tool converts everything to m³/s internally, so the emission rate always comes out in ouE/s (and ouE/h for convenience).
How do I get the odour concentration to enter here?
From dynamic olfactometry on a sample taken at the source, expressed in ouE/m³. If you only have a dilution-to-threshold ratio, convert it first with the odour concentration calculator, then bring the ouE/m³ figure here.
What about area sources like lagoons or piles?
Area sources are usually characterised as a Specific Odour Emission Rate per square metre using a flux hood or wind tunnel, then scaled by area. This tool handles the point/ducted case (concentration × volumetric flow); an area source needs that extra step.
Screening estimates only — not a substitute for accredited EN 13725 olfactometry, dispersion modelling, or regulatory advice.