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 evaluates how odours from industrial, agricultural, commercial kitchens or waste operations may impact sensitive receptors. The techniques used as part of an odour assessment can include odour dispersion modelling, dynamic olfactometry, sniff testing surveys, and odour nuisance investigations.
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:
- Odour Impact Assessments (OIA)
- Odour risk assessments
- Odour mitigation and management plans
- Routine odour surveys and sniff tests
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 filtration system would depend on various design factors, as well as the classification of the risk of an adverse odour impact, which would in turn be determined by an odour risk assessment. In most circumstances, this is as follows:
Low risk: grease filters + carbon
Medium risk: HEPA or fine particulate filters + carbon
High risk: ESP units, UV-ozone filtration + carbon
Very high risk: Multi-stage filtration systems
Are carbon filters enough?
Though Carbon filters do come in useful, they are usually not used alone for Fried foods, Charcoal grills and High-volume takeaways. Most councils would expect ESP + carbon + UV systems.
What is an ESP?
An Electrostatic Precipitator removes grease, smoke and fine aerosols before they reach the carbon filters — often mandatory for BBQ, fried food, wok kitchens, and charcoal cooking.
What is UV-ozone filtration?
UV-ozone units chemically break down odour compounds and grease vapours, and are often paired with ESP systems in high-risk cooking environments.
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?
OdourScope assessments adhere to recognised standards including:
- Environment Agency H4 Odour Management Guidance
- Institute of Air Quality Management (IAQM) Odour Guidance
- EMAQ+ guidance on controlling odour and noise from commercial kitchen exhaust systems
- BS EN 13725 (dynamic olfactometry)
- Local planning authority requirements
- Sector-specific guidance for waste, agriculture & industrial processes
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
How long does an odour assessment take?
Timescales vary depending on scope, but typical durations are:
Desktop risk assessments: 3–7 days
Fast-track services may be available depending on complexity.
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.