Odour Risk Assessments for Commercial Kitchens
20-07-2026
What Is a Commercial Kitchen Odour Risk Assessment?
A Commercial Kitchen Odour Risk Assessment, more commonly known as a Kitchen Odour Risk Assessment, or KORA, is a process for quantifying the odour risk from a commercial kitchen operation, such as a restaurant, takeaway, pub or club. This is often a desk-based exercise to help develop the design of a new commercial kitchen or to support a planning application for a new food business.
For existing kitchen operations, where odour issues have been reported in the community, or where a change of use is proposed, it may also be possible to supplement the desk-based work with a site odour survey, which is often referred to as a ‘sniff test’.
What is the purpose of an odour risk assessment?
An odour risk assessment identifies the source and nature of cooking odours and reviews how odour emissions are managed through the kitchen extraction system, where they are discharged to the environment, and whether nearby sensitive receptors (e.g. residential properties) could be affected.
All of these factors combine to determine an overall odour risk for the kitchen being assessed. The level of odour risk determined during the assessment process subsequently establishes the level of odour mitigation/abatement that will be required to suitably reduce any odour emissions such that they would be unlikely to cause a nuisance at nearby sensitive uses.
Why are odour risk assessments important?
Problems associated with nuisance odour emissions from commercial kitchens are common, especially in built-up, urban areas where sensitive uses, such as houses and apartments, are located near to, or even directly above, food premises. When designing a new commercial kitchen extraction system or applying for planning approval for a new commercial kitchen operation, it is important that any potential odour risks are understood and managed, and that odour risk assessments and plans or designs are discussed and agreed with the local planning authority (LPA).
In cases where odour issues are not appropriately addressed and consulted on with the LPA, planning approval could be delayed or refused or, in the case of existing operations, statutory enforcement action could be taken by the local authority against the food business.
Which businesses are most likely to need one?
The most common businesses that are likely to require a Commercial Kitchen Odour Risk Assessment are restaurants, takeaways, pubs and clubs.
There are generally a greater number of these types of premises in urban areas, which also have higher densities of residential and other sensitive land uses in proximity to such businesses. Late night trading hours for some of these operations enhance the risks around odour nuisance in the local community.
When Do You Need an Odour Risk Assessment?
Depending on the nature of the proposal, you may need a kitchen odour risk assessment when designing a new commercial kitchen extraction system (i.e. pre-planning stage), applying for planning approval for a new commercial kitchen operation (i.e. planning stage) or potentially in response to imposed planning conditions or to odour issues reported in the community due to an existing food premises (i.e. post-planning or operational stage).
Planning permission for new restaurants and takeaways
When applying for planning permission for a new commercial food operation, it is important that any potential odour risks are assessed so that appropriate levels of mitigation can be implemented to the satisfaction of the LPA. It is possible that a planning application will be delayed or even refused if important information on potential odour issues and mitigation options is not included in the planning submission to the LPA.
It is always advisable to discuss kitchen plans, odour risks and abatement options with the LPA before submitting a planning application.
Change of use applications
When applying for a change of use for a commercial food operation it is important that any potential odour risks are assessed so that appropriate levels of mitigation can be implemented to the satisfaction of the LPA. It is possible that a change of use application will be delayed or even refused if important information on potential odour issues and mitigation options is not presented to the LPA with the change of use submission.
For change of use applications, the change in potential odour impacts between the existing and proposed use is important. If the existing use is already a food premises, a ‘sniff test’, in addition to the desk-based odour risk assessment, may be useful to establish the existing odour climate.
Local authority planning requirements
As responsibility for the enforcement of statutory nuisance for odour usually lies with the local authority environmental health department, planning applications to LPAs for commercial kitchen operations must be robust and follow relevant guidance and best practice methods for odour risk assessment and odour survey and monitoring work.
The key odour risk assessment guidance that consultants and local authorities refer to in the UK was originally published by Netcen/AEA Technology on behalf of the Department for Environment Food & Rural Affairs (DEFRA) and has been reproduced and updated in a document now commonly known as the EMAQ+ guidance, which considers both odour and noise issues for commercial kitchens.
How Is a Commercial Kitchen Odour Risk Assessment Carried Out?
A Commercial Kitchen Odour Risk Assessment is usually a desk-based activity that considers several factors to determine an overall level of odour risk for a particular kitchen extraction system. The determined odour risk subsequently drives requirements around odour abatement technology to suitably minimise the potential odour risk to the local community.
Odour surveys (‘sniff tests’) can sometimes be helpful to supplement the desk study by empirically establishing the odour climate in and around an existing food premises.
Assessing the source of odours
The risk assessment process considers the size of the kitchen (number of covers) and the type of cuisine being cooked (e.g. cold sandwiches versus fried foods such as fish and chips). It also considers how well dispersed the kitchen extract odours are and how close sensitive receptors are to the odour source or point of discharge.
Each of these elements is given a numeric score, ranging from small to large (for the size of the kitchen), low to very high odour potential (for the cooking type/grease loading), very poor to good (for the extract dispersion) and close/nearby to far/distant (for the proximity of sensitive receptors).
The higher the determined score, the higher the potential odour risk.
Evaluating the level of odour risk
Once the odour risk for each of the four key elements has been determined, an overall numeric risk score is calculated, which is the sum of the four individual scores. The overall odour impact risk ranges from low to medium, through to high and very high, each of which has a corresponding level of odour control/abatement that should be installed for the kitchen extraction system being proposed.
Where a kitchen is already in operation, the outcome of the risk assessment may result in the requirement to retrofit or upgrade the already installed odour abatement system to better manage odour emissions.
Preparing recommendations for planning
The ultimate outcome of the risk assessment process is a set of recommendations on odour abatement/mitigation relative to the identified odour risk for the kitchen in question. A report submitted to the LPA, detailing the odour risk assessment process, including any assumptions on the number of covers, cuisine and cooking type, discharge location and height, and proximity of sensitive receptors, together with recommendations on odour abatement/mitigation will assist the LPA to determine whether the proposal is acceptable.
If such an assessment is not done at pre-planning or planning stage, there is a risk that potentially costly retrofit works could be required on an already installed kitchen extraction system, especially if odour complaints are received from the local community. For low risk proposals (e.g. small, cold food operations) the LPA may take a pragmatic view on whether any odour abatement technology needs to be implemented.
What Does an Odour Risk Assessment Consider?
A Commercial Kitchen Odour Risk Assessment considers four key elements: the size of the kitchen, the type of food being cooked and how it is cooked, how and where the kitchen extract is discharged to, and where sensitive receptors are located.
Kitchen size
The size of the kitchen is one of the key factors in determining the odour risk for a food premises. Large operations (more than 100 covers) or large takeaway outlets pose the greatest potential odour risk. Small takeaways and smaller restaurants with fewer than 30 covers are comparatively low risk.
Cooking methods and cuisines
Foods with higher levels of fat/grease, such as burgers, fish and chips and fried chicken tend to be more odorous than cold foods such as sandwiches and salads. Cooking techniques such as frying and grilling over solid fuels (such as charcoal or wood) also tend to result in higher odour emissions than cooking techniques such as reheating/microwaving.
The EMAQ+ guidance indicates that pub food and food cooked over solid fuels (such as some Middle Eastern cuisines) tend to pose the greatest odour risk.
Kitchen extraction discharge
The ventilation rate of the kitchen extract system and the height/location of the discharge point are important in determining the odour risk for a commercial kitchen. If the kitchen extract system operates at a ventilation rate of 10-15 m/s and discharges above the eaves or ridge of the property, the dispersion is likely to be moderate to good. Low-level discharges, such as into a courtyard, and/or low extraction speeds (<10 m/s) are likely to lead to poor dispersion and consequently increase the odour risk.
Proximity of receptors
The source-pathway-receptor model indicates that, even if there is an odour source (commercial kitchen extraction system) and a pathway (the distance and environment between the source and receptor) there can be no impact if there is no receptor that can be affected by the odour.
The closer a sensitive receptor is to the kitchen extraction discharge point, the greater the odour risk. The EMAQ+ guidance suggests that sensitive receptors within 20 m of the discharge point are at greatest risk, and even at 100 m from the discharge point there is still a risk, albeit a much lower risk, of adverse odour impacts at sensitive receptors.
Odour Control Measures for Commercial Kitchens
The level of odour risk determined during the assessment process subsequently establishes the level of odour mitigation/abatement that will be required to suitably reduce any odour emissions such that they are unlikely to cause a nuisance at nearby sensitive uses. According to the EMAQ+ guidance, a commercial kitchen extraction system should include suitable stack dispersion and an adequate level of particulate and odour control.
The design of the kitchen extraction system should deal with two phases of contamination: the particulate phase (grease, smoke, hydrocarbons/VOCs) and the gaseous phase (odour). The EMAQ+ guidance states that the particulate phase needs to be removed prior to the treatment of the gaseous phase and the subsequent discharge to atmosphere via the stack or vent.
The EMAQ+ guidance provides minimum odour control requirements for commercial kitchens. These requirements apply to the discharge stack and the treatment of the kitchen extract air stream. These requirements vary depending on the determined odour risk.
Extraction discharge
Ideally, the extracted air should be discharged at a height not less than 1 m above the roof ridge of any buildings within 15 m of the stack/vent serving the commercial kitchen. If this is not possible due to physical, planning or other constraints, the extracted air should ideally be discharged not less than 1 m above the roof eaves or dormer window of the building housing the commercial kitchen.
In this instance a higher level of treatment of the kitchen extract air (see below) may be necessary. If neither of the ideal stack discharge scenarios are achievable, an even higher level of kitchen extract air treatment may be required.
Treatment of extract air stream
Commercial kitchens with a low to medium odour risk should employ, as a minimum, fine filtration or Electrostatic Precipitation (ESP) to deal with the particulate phase, followed by carbon filtration for the gaseous phase. The carbon filters should have, as a minimum, a 0.1 second residence time. Alternatively, a system of fine filtration followed by a counteractant/neutralising system may achieve the same level of odour control.
Commercial kitchens with a high odour risk should employ, as a minimum, fine filtration or ESP, followed by carbon filtration. The carbon filters should have, as a minimum, a 0.2 to 0.4 second residence time. Alternatively, a system of fine filtration or ESP followed by a UV ozone system may achieve the same level of odour control.
Where a commercial kitchen’s odour risk is very high, the minimum requirement is fine filtration or ESP with carbon filtration downstream, in this case, with a residence time of at least 0.4 to 0.8 seconds. Equivalent odour control may instead be achieved by pairing fine filtration or ESP with either a UV ozone system or a counteractant/neutralising system.
Common Planning Issues and How to Avoid Them
When applying for planning permission for a new commercial food operation it is important that any potential odour risks are assessed so that appropriate levels of mitigation can be implemented to the satisfaction of the LPA. It is possible that a planning application will be delayed or even refused if important information on potential odour issues and mitigation options is not presented to the LPA with the planning submission.
It is always advisable to discuss kitchen plans, odour risks and abatement options with the LPA before submitting a planning application. Moreover, instructing an environmental odour specialist, such as Phlorum, to undertake a Commercial Odour Risk Assessment early in the process can help reduce or avoid planning issues later in the project programme.
Inadequate odour mitigation
Inadequate abatement of particulate and gaseous phases of the kitchen extraction air stream may lead to odour issues in the local community and complaints made to the operator and/or the local authority. This could lead to expensive odour investigation work and/or the redesign and retrofit of already installed kitchen extraction systems.
Odour emissions leading to nuisance may lead to enforcement action by the local authority or, potentially, civil litigation action could be taken by affected third parties, which could be costly for the operator.
Poor extraction discharge
Poor design in terms of the extraction ventilation rate and/or the location of the discharge point (stack/vent) may lead to odour issues in the local community and complaints made to the operator and/or the local authority. This could lead to expensive odour investigation work and/or the redesign and retrofit of already installed kitchen extraction systems.
Odour emissions leading to nuisance may lead to enforcement action by the local authority or even civil action, which could be costly for the operator. For these reasons, it is recommended that a suitable odour risk assessment is carried out to inform the design of kitchen extract systems and associated odour control/abatement.
Delays to planning applications
When applying for planning approval for a new commercial kitchen operation, it is important that any potential odour risks are understood and managed, and that odour risk assessments and plans/designs are discussed and agreed with the LPA.
In cases where odour issues are not appropriately addressed and adequately consulted on with the LPA, planning approval could be delayed, refused, or conditioned in a way that would make operating the commercial kitchen operationally difficult.
Complaints and statutory nuisance
Problems associated with nuisance odour emissions from commercial kitchens are common, especially in built-up urban areas where sensitive uses, such as houses and apartments, are located near or even directly above food premises.
In the case of existing operations, the LPA could take statutory enforcement action against the food business. This could take the form of an improvement notice, restrictions on operating hours or the cessation of operations until the odour issues are rectified.
In all cases, this could lead to expensive investigations and design and engineering works for the operator.
Why Choose Phlorum for Your Commercial Kitchen Odour Risk Assessment?
Phlorum’s air quality consultants are highly skilled and experienced in all forms of odour assessment, including Commercial Kitchen Odour Risk Assessments and Expert Witness work.
We have provided technical odour expertise and advice to developers, planning consultants, architects and large restaurant chains and takeaways for commercial kitchen projects of varying scales and at various stages in the design and planning process. We have also undertaken odour risk assessments for already operational commercial kitchen premises where odour complaints have been received from the local community.
We work with our clients and LPAs to reduce potential odour risks associated with commercial kitchens, allowing our clients to plan for, and ultimately operate, restaurants, takeaways, pubs and clubs without adversely impacting the communities in which they are located.
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