Guide to H4 Odour Management: What does the Environment Agency say about odour control?

If your production facility produces odour you may require an environmental permit and have a duty to take appropriate steps to minimise the odour. In this guide we explain what the Environment Agency says about odour control in its H4 Odour Management guidance, your responsibilities and how FEG can help you meet your odour management requirements.

H4 Odour Management

What does the Environment Agency say about odour?

Odour that extends beyond the boundaries of a production facility and causes a nuisance to the surrounding area is considered pollution and can severely impact the quality of life of those living nearby. If these stakeholders complain it can have serious implications for the company, including damage to the brand reputation if complaints are escalated to the media, hefty fines and even the threat of closure if licenses are revoked.

And it’s not just the neighbours odour-producing sites need to worry about. Offensive odour can have a serious impact on employees too.

To combat these issues, the Environment Agency has strict rules around businesses’ responsibilities when it comes to odour, outlined in its H4 Odour Management guidelines.


You must prevent or, where that is not possible, minimise odour if you have a waste, mining waste or installation permit. To do this you must use all appropriate measures, normally including:

• restricting raw materials that are likely to cause odour, like putrescible or already putrid biodegradable waste
• minimising quantities and storage times for odourous or potentially odourous materials
• managing materials and processes in ways which minimise the production of odourous chemicals
• working within the effective operational capacity of your site
• providing effective containment and abatement for odourous materials and activities

You must respond effectively and proportionately to any process monitoring which indicates a problem, or reports from the community of odour pollution.

The Environment Agency’s H4 Odour Management document provides additional detailed guidance, outlining:

  • Permit conditions
  • How to assess the level of odour pollution
  • Control measures
  • How to monitor odour

Your responsibilities

This diagram below outlines the level of odour and the steps that need to be taken at each stage. It’s worth noting that if circumstances change, e.g. a new housing development is built nearby, your odour permit may need to change too and you may wish to consider this when designing your boundary.

As part of the odour assessment process involved in obtaining an environmental permit, you must submit an Odour Management Plan (OMP) to demonstrate that you are taking adequate steps to manage the odour.

h4 odour management levels

Control measures

The OMP should include the measures you plan on taking to control the odour. This includes:

  • How you plan to manage odourous materials – For example, what will the process be when an odourous material (i.e. animal by-products) arrives on site and how will they be stored? The H4 Odour Management guidance states that you should ensure any odourous materials arriving at your facility should be treated promptly and stock levels should be kept to a minimum.
  • Evaporation – This section covers how you plan on reducing the rate of odourous chemicals evaporating into the air. The Environment Agency provides suggestions for steps you might take, including temperature, treating the materials and minimising disruptive activities such as shedding or screening.
  • Containment – If it isn’t possible to avoid producing high levels of contaminated air, you will need to contain it before treating it. This section includes details on how you plan on containing the odour – e.g. airlocks, window/door opening procedures and pipework.
  • How the odour will be treated – Here you should outline the techniques and equipment you plan on using to treat the odour. This is likely to include adsorption (e.g. activated carbon), scrubbers, biological treatment methods or thermal treatment. You can read more about odour treatment methods in our guide to industrial odour control.
  • Transport and dispersion – This covers any plans you have to use dispersion methods to reduce odour. It may be possible to minimise odour by using dispersion modelling (i.e. using high stacks to allow odourous emissions to disperse before they reach the ground or increasing the physical distance to the receptors). You could also consider the timing of your operations based on factors like wind direction or specific times of day.
  • Community engagement – The OMP needs to include details on how you will engage with your neighbours to mitigate concerns and complaints. The H4 Odour Management notes put emphasis on the importance of fostering good relationships with local stakeholders and building positive channels of communication.
  • Complaint management – You’ll need to include details of how you will respond to any complaints that arise. The Environment Agency will want to see evidence that you will respond and take necessary action quickly, as well as how you will record complaints and subsequent investigations.
  • Stopping/reducing operations – Your OMP must demonstrate that you are prepared to stop or reduce site operations if an investigation resulting from a complaint determines you need to. You should include details of contingency plans, for example it may be possible to suspend certain activities while remedial action takes place.
  • Accident management – The environmental permit may require you to maintain an accident management plan to address any accidents caused as a result of odour, such as how you will respond to accidents and who is responsible for taking preventative action following an incident.
guide to dry filtration systems


H4 Odour Management also outlines steps you must take to monitor any odourous emissions to determine how effective your odour control measures are.

The guidance notes go into great detail about the type of monitoring you could carry out, but essentially it will depend on the actual or potential impact on the local community. You’ll also need to consider factors such as whether the odour is episodic (i.e. only happening at certain times), weather conditions, monitoring points and detection limits of instruments – emissions could be below the detection limit but still noticeable by people.

Monitoring also covers complaint monitoring, as complaints are an obvious indication that the odour is causing a nuisance. 

According to the Environment Agency, monitoring can take the form of:
  • Sniff testing
  • Odour diaries and community surveys
  • Sampling
  • Chemical monitoring
  • Measuring odour surrogates and process controls
  • Fugitive emissions

Regardless of the type of monitoring, it’s essential that detailed records are kept, including information such as date/time, weather conditions, method, how any samples were collected stored, and any process limitations.

How FEG can help meet your H4 Odour Management responsibilities

We can provide support at every stage of the odour management journey – from initial consultations and planning to odour monitoring and abatement solutions. 

Odour is a complex problem to solve, and each site has unique requirements. We take a holistic view of odour control projects, drawing on our years of expertise and engaging with stakeholders to develop a bespoke, multi-faceted solution that will satisfy your environmental permit requirements.

Environmental surveys

We conduct environmental surveys to ensure employee wellbeing, support planning permissions and resolve conflict with the wider community.

Our process-driven approach is key to helping us understand the source of the problem and, unlike many survey providers, our expertise allows us to understand the practical application behind the results and recommend and install solutions.

Odour control solutions

We can design and supply a full odour abatement system that includes not only the scrubber but incorporates all required pipework, pumps, chemical dosing and storage systems, extraction equipment, stack and control panel requirements.

industrial odour control solution
Featured Project
Successful removal of environmental notice thanks to FEG odour control solution

Our client had received an environmental notice as a result of odour from its proteins frying factory. We developed a bespoke system to tackle all elements of the problem, resulting in the successful removal of the notice and allowing our client to continue operating. 

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FEG odour control services

If you’ve received an environmental notice or are navigating your odour permit journey, our expert team can offer support and guidance. Get in touch to find out about our odour abatement services and how we can help with H4 Odour Management.