Dispersion Modelling
Air Quality and Odour Dispersion Modelling for Planning, Environmental Permits and Compliance Evidence
Dispersion modelling predicts how emissions to air disperse and what ground-level concentrations or odour impacts may occur at receptors. It is used to support planning applications, Environmental Permit risk assessments, and compliance decisions where screening alone is not sufficient. A robust modelling assessment provides defensible evidence, clear impact interpretation, and practical mitigation actions aligned to current UK guidance.
When Dispersion Modelling Is Required
Dispersion modelling is typically required where:
- Planning applications need an Air Quality Assessment supported by modelling (see Air Quality Assessments)
- Environmental Permit risk assessment cannot screen out emissions impacts
- New plant, changes in emissions, or abatement modifications require updated impact evidence
- There are sensitive receptors nearby (residential, schools, hospitals, ecological receptors)
- Odour constraints exist and modelling is needed (see Odour Dispersion Modelling)
- Stack height, discharge location or operational controls need evidence-based justification
Purpose of Dispersion Modelling
The purpose is to provide an objective, quantitative assessment of impact at receptors so decisions can be made defensibly. For planning, this supports impact significance and mitigation design. For permitting, it supports risk assessment, stack height selection, screening outcomes and regulator confidence.
What Dispersion Modelling Typically Covers
Depending on scope, dispersion modelling can include:
- NO2, PM10, PM2.5 and other air quality determinands for planning assessments
- Process contributions and total concentrations at receptors
- Stack height sensitivity and discharge parameter testing
- Odour modelling where odour units and frequency metrics are required
- Scenario testing (baseline, future year, with/without mitigation, different operating modes)
How Dispersion Modelling Works in Practice
A defensible modelling assessment depends on transparent inputs, clear assumptions and a structured verification approach. We scope the model to the decision it needs to support, select appropriate meteorological and background data, define receptors and scenarios, and then present outputs in a planning- or permit-ready format with clear conclusions and mitigation recommendations.
Standards, Guidance and Regulatory Context
Dispersion modelling for UK planning and compliance is commonly aligned to:
- EPUK & IAQM: Planning for Air Quality Guidance (PDF)
- IAQM: Guidance on the assessment of odour for planning (PDF)
- GOV.UK: Risk assessments for your environmental permit (permitting context)
What the Service Delivers
- Model scope and methodology aligned to planning or permitting objectives
- Clear definition of assumptions, inputs, receptors and scenarios
- Results tables and maps suitable for reports and stakeholder review
- Impact interpretation and significance conclusions appropriate to the context
- Mitigation recommendations and scenario testing where required
- A clear, defensible report suitable for submission or regulator engagement
Limitations and Scope
Dispersion models are only as robust as the input data and assumptions. Where uncertainty is material, we make it explicit and recommend proportionate sensitivity testing or additional evidence to strengthen confidence.
FAQs
Is dispersion modelling always required for planning?
Not always. It depends on development type, receptors, baseline air quality and local authority expectations. Many higher-risk schemes require modelling to support a defensible assessment.
Can dispersion modelling support Environmental Permit applications?
Yes. It is commonly used when emissions risk cannot be screened out and when stack height or emission impacts require quantitative justification.
Can modelling help reduce mitigation cost?
Yes. Scenario testing can show what mitigation is necessary (and what is not), supporting proportionate controls and avoiding over-design.
Do you model odour as well as air quality?
Yes. Odour modelling can be delivered where odour emission inputs and assessment objectives are defined.
Need modelling evidence that stands up to scrutiny?
We can deliver clear, guidance-aligned dispersion modelling with defensible assumptions and practical mitigation actions. Request a quote today and hear back within 24 hours.
