Odor Impact Distance Estimator
A first-pass screen of how far a source’s odour travels before it falls to an acceptance criterion — from its emission rate and a simple dispersion factor.
Screening separation distance
A first-pass inverse-square screen: with C(x) = OER / (F·x²), the distance at which the concentration meets your criterion is x = √(OER / (F·Ctarget)). It is a screening number only — a real separation distance needs site-specific dispersion modelling.
A screen, not a model
Concentration downwind of a source falls off roughly with the square of distance as the plume spreads and mixes. That lets you turn an emission rate and an acceptance criterion into an order-of-magnitude separation distance in a single step — useful for a quick feasibility check before committing to a full study.
The catch is the dispersion factor: it hides all the physics a real model handles explicitly — wind climate, atmospheric stability, terrain, building downwash, and the averaging time behind the criterion. Treat the distance as a ballpark to be confirmed, never as a decision.
Frequently Asked Questions
What does this estimator actually compute?
It gives a rough distance from an odour source at which the ground-level odour concentration falls to a criterion you choose. It rearranges a simple inverse-square screening relation, C(x) = OER / (F·x²), to x = √(OER / (F·C_target)).
What is the screening dispersion factor F?
F is an effective parameter (in units of m/s) that rolls wind speed and plume spread into one number. It is deliberately crude — a real assessment uses a dispersion model with meteorology, terrain, and building effects rather than a single lumped factor. Adjust F to match your screening basis.
What acceptance criterion should I use?
Odour criteria are set by local regulators and typically fall in the range of roughly 1 to 10 ouE/m³ as a short-term concentration at a defined percentile, with stricter values for more sensitive land uses. Use the value your jurisdiction specifies; the tool doesn't assume one.
Where does the emission rate come from?
From the source's Odour Emission Rate in ouE/s — odour concentration times volumetric flow. You can produce that with the odour emission rate calculator and bring the figure here.
Can I use this to set a real setback or buffer?
No. This is a screening-level sanity check, not a basis for planning decisions or separation distances. Regulatory separation distances come from validated dispersion modelling and the applicable guideline, carried out by a qualified practitioner.
Screening estimates only — not a substitute for accredited EN 13725 olfactometry, dispersion modelling, or regulatory advice.