Odour Risk Assessment FAQ Hub
Your central resource for understanding odour assessments, regulatory requirements, planning expectations, methodology, and best practices.
This page is designed to support clients, planners, developers, environmental consultants, and local authorities seeking clear and authoritative information.
FAQ
What is an odour assessment?
An odour assessment considers the potential effects of odour from existing or proposed activities on neighbouring properties and other sensitive receptors. Depending on the nature of the development, this may involve a desktop review, site-based odour surveys, qualitative risk assessment or more detailed techniques such as atmospheric dispersion modelling.
Assessments are commonly undertaken to support planning applications involving agricultural operations, wastewater treatment works, waste management facilities, industrial processes and commercial kitchens, as well as residential developments proposed near existing odour sources.
When is an odour assessment required?
You may need an odour assessment for:
- Planning applications for new or expanding developments
- Environmental permit applications (EA, SEPA, NRW)
- Assessing potential odour complaints
- Regulatory compliance with industrial or waste management activities
- Due diligence for property development
- Local authority requests following nuisance allegations
- Industries such as waste, wastewater, agriculture, food production, composting, chemical manufacturing, and energy often require odour assessments.
What types of odour assessments do we offer?
OdourScope provides a range of odour consultancy services tailored to the nature of the development and the assessment requirements. These include Odour Impact Assessments for planning applications, site-based odour surveys, qualitative source–pathway–receptor assessments, agricultural and farm odour assessments, commercial kitchen odour risk assessments and associated mitigation advice.
The appropriate scope of work is established with regard to the potential odour sources, nearby sensitive receptors and any specific concerns raised by the Local Planning Authority or Environmental Health Officer.
What is a commercial kitchen odour risk assessment?
A commercial kitchen odour risk assessment evaluates cooking odours, grease, smoke, and fumes produced by restaurants, takeaways, cafés, pubs, and dark kitchens. It determines the level of odour mitigation required by DEFRA kitchen odour guidance and local authority planning policies and is essential for restaurants, takeaways, dark kitchens, pub kitchens, and cloud kitchen delivery hubs.
When is a kitchen odour assessment required?
A kitchen odour risk assessment is typically required for:
- New restaurants & takeaways
- Changes of use involving hot food
- Dark kitchen approval
- Extraction system upgrades
- Planning conditions related to odour
What determines the odour risk rating?
Factors include:
- Cuisine type (frying, grilling, wok cooking, charcoal grilling)
- Cooking volume & hours
- Ventilation discharge height
- Proximity to homes
- Filtration system efficiency
- Number of covers per day
What filtration system do I need?
The appropriate filtration and odour-control system will depend on the cooking activities, extraction arrangement, discharge location and proximity of neighbouring sensitive receptors. A commercial kitchen odour risk assessment can help establish the level of odour control required, taking account of the relevant EMAQ+ guidance and site-specific circumstances.
Depending on the assessment findings, suitable measures may include grease and particulate filtration, electrostatic precipitation, activated carbon treatment and other appropriately designed odour-abatement systems. The final specification should also consider airflow rates, maintenance requirements and the suitability of the proposed installation.
Are carbon filters enough?
Activated carbon can provide effective treatment of certain cooking odours when correctly specified and maintained, although its performance will depend on factors such as the type of emissions, particulate loading, airflow, contact time and condition of the carbon media.
For higher-intensity cooking operations, particularly those involving significant grease and smoke emissions, additional upstream particulate treatment may be necessary to protect the carbon system and maintain its effectiveness. The appropriate arrangement should therefore be established through an assessment of the proposed kitchen activities and extraction design rather than assuming a standard filtration configuration will be suitable for every premises.
What is an ESP?
An electrostatic precipitator (ESP) is an air-cleaning device used to remove airborne grease, smoke and fine particulate matter from commercial kitchen exhaust air. By reducing particulate loading, an ESP can help protect downstream odour-treatment equipment, including activated carbon filters, although it does not provide complete treatment of gaseous cooking odours on its own.
The need for an ESP will depend on the cooking processes, extraction characteristics and level of odour control required.
What is UV-ozone filtration?
UV-based treatment systems may be incorporated into commercial kitchen extraction arrangements to assist with the treatment of grease vapours and certain odorous compounds. Their effectiveness depends on the design, operating conditions and characteristics of the exhaust air, and they should not be assumed to provide adequate odour control in every application.
Where ozone is generated or introduced, particular attention is required to equipment safety, residual ozone, maintenance and the suitability of the proposed discharge arrangements. The selection of any UV or ozone-based system should therefore be supported by appropriate technical evidence.
How often should filters be replaced?
A typical maintenance schedule can be considered to be as follows, though the best practice is to confirm with the manufacturer.
Grease filters: weekly
Carbon filters: every 3–6 months
ESP: monthly cleaning
UV lamps: annually
Do dark kitchens require stronger odour control?
Yes. This is mostly due to the fact that Dark kitchens often have high cooking volumes, close proximity to residential areas, multiple cooking stations, as well as long operating hours.
What guidance do odour assessments follow in the UK?
The applicable guidance depends on whether the assessment is being prepared for a planning application, environmental permitting or a specific operational requirement.
For planning applications, odour assessments are generally informed by the IAQM Guidance on the Assessment of Odour for Planning (2026, Version 2.0), together with relevant planning policy and local authority requirements. Commercial kitchen assessments may additionally refer to EMAQ+ guidance on kitchen extraction and odour control.
For activities regulated under the environmental permitting regime in England, the Environment Agency's current guidance, Odour management: comply with your environmental permit, may apply. This replaced the former H4 Odour Management guidance in December 2025.
Other standards, including BS EN 13725 for dynamic olfactometry, may be relevant where specific odour measurement techniques are required.
What is odour modelling?
Odour modelling uses dispersion modelling software to predict how odours travel through the air under different weather conditions.
It considers:
- Source strength (emission rate)
- Stack height & release characteristics
- Site layout
- Meteorological data
- Sensitive receptor locations
What is a qualitative odour survey?
A qualitative odour survey involves site-based observations to establish the nature of existing odour conditions and the potential for emissions to affect nearby sensitive receptors. Depending on the project, observations may be undertaken around potential odour sources, within the proposed development site and at representative receptor locations, with consideration given to odour character, intensity, duration, source activity and prevailing meteorological conditions.
The findings are considered alongside other available information, including operational practices, surrounding land uses and meteorological evidence, to provide a proportionate assessment of potential odour effects. This approach is particularly useful where existing odour conditions need to be understood before a planning application is submitted.
Do I need an odour assessment for development near a farm?
An agricultural odour assessment may be required where new residential or other sensitive development is proposed close to an existing farm, particularly where livestock housing, manure storage, slurry handling or other potentially odorous activities are undertaken nearby.
Although odour may form part of normal agricultural operations, the planning process must consider whether future occupants are likely to experience unacceptable effects. The assessment therefore considers the characteristics of the existing activities, separation distances, meteorological conditions and sensitivity of the proposed development, together with site-based observations where appropriate.
Where potential constraints are identified, the findings can help inform the proposed layout and establish whether further assessment or mitigation measures should be considered.
Can an odour assessment help address an Environmental Health Officer's objection?
Where an Environmental Health Officer has raised concerns about potential odour impacts, a suitably scoped assessment can provide the technical evidence needed to address the matters identified during the planning consultation process.
Depending on the circumstances, this may involve reviewing existing site conditions, undertaking odour surveys, assessing the relationship between potential sources and sensitive receptors or evaluating proposed mitigation measures. The findings can then be presented in a report explaining the assessment methodology, likely effects and any recommendations considered necessary.
Although the final planning decision rests with the Local Planning Authority, a proportionate and technically supported assessment can assist in resolving outstanding odour concerns.
How long does an odour assessment take?
The timescale for an odour assessment will depend on the nature of the project, the information available and whether site-based observations or additional technical analysis are required.
A straightforward desktop assessment can generally be completed more quickly than an investigation requiring site visits, operational observations or atmospheric dispersion modelling. Where a planning application is already in progress, we can review the relevant requirements and advise on an appropriate programme, subject to our survey and reporting availability.
What information do you need to start an odour assessment?
Common inputs include:
- Site boundary and layout plans
- Process descriptions
- Operating hours
- Emission data (if available)
- Proposed development plans
- Local meteorological data
- Historic complaint records (if relevant)
What are “odour units” (OU)?
Odour units (OU/m³) quantify odour concentration based on human sensory thresholds.
1 OU/m³ equals the concentration at which 50% of people can detect the odour.
Can odour issues be mitigated?
Yes. Common odour control solutions include:
- Activated carbon filtration
- Biofilters & bioreactors
- Chemical scrubbers
- Containment & ventilation optimisation
- Process changes
- Improved housekeeping & waste handling
- Odour Management Plans (OMPs)
OdourScope provides tailored mitigation strategies and costed recommendations.
How much does an odour assessment cost?
The cost of a survey varies based on the scope of work required by that specific project. Just get in touch, we offer free consultations
What is an Odour Management Plan (OMP)?
An OMP outlines how a site will prevent, reduce, and control odour emissions.
It typically includes:
- Source identification
- Mitigation measures
- Operational controls
- Monitoring requirements
- Complaint management procedures
- Maintenance schedules
OMP documents are often mandatory for Environmental Permits.