Intensive farming risk assessment for your environmental permit
What you must do to carry out a risk assessment if you're a farmer applying for a bespoke permit for intensive farming.
Applies to England
You must follow this guide if you’re applying for a permit or to change (vary) a permit for intensive farming under the Environmental Permitting Regulations.
Read the risk assessment overview first. It explains the other steps to take in risk assessment and whether you need to read this guide.
As part of your risk assessment you must assess the following emissions:
- ammonia
- odour
- noise
- dust and bioaerosols (airborne particles that contain living organisms)
This is to check if they are likely to affect people or parts of the environment that could be harmed by emissions from your farm (called ‘receptors’).
Pre-application discussion
You can request pre-application advice to arrange a pre-application discussion for your intensive farming permit.
In this discussion, the Environment Agency will:
- tell you about the application process
- identify nature conservation sites and neighbours close to your farm who will need to be considered in the environmental risk assessment
The Environment Agency will also tell you what should be included in the permit, for example:
- relevant buildings
- fuel storage
- carcass incinerators
- slurry storage
Ammonia screening assessment
You will need to request an ammonia screening assessment for your proposal.
You’ll need to give information to the Environment Agency to help them:
- identify nature conservation sites within the relevant screening distances
- predict expected ammonia emissions resulting from your proposal
- assess the potential impact of your proposal on nearby nature conservation sites
You must have a completed ammonia screening assessment before:
- applying for a new intensive farming permit
- applying to change (vary) an existing permit that has the potential to affect ammonia emissions
Ammonia emission factors and standards
The Environment Agency will work out the most appropriate ‘emission factors’ based on your livestock type and housing system. You can check the standard ammonia emissions factors they use as a starting point for screening assessments.
If you operate a housing system not listed in the standard ammonia emission factors, you may need to give evidence of a site-specific ammonia emission factor as part of your permit application.
You can adjust these standard emission factors in scenarios where you use:
- a lower crude protein content in the animal’s diet
- other ammonia mitigation measures
- an occupancy rate significantly lower than the standard rate
You must have agreement from the Environment Agency before using any bespoke emission factors. During the pre-application discussion, your permitting officer will tell you whether a bespoke factor can also be applied at the screening stage. The Environment Agency will use standard emission factors for ammonia screening unless they have previously agreed otherwise.
The Environment Agency will assess your ammonia emissions against 3 standards to check the risk of air pollution:
- ammonia critical level
- nutrient nitrogen critical load
- acidity critical load
The Air Pollution Information System explains critical levels and loads.
Ammonia screening thresholds
The Environment Agency will identify if there are any protected nature conservation sites close to your farm based on the following screening distances.
| Nature conservation site designation | Distance from site in km | Lower threshold % | Upper threshold % |
|---|---|---|---|
| Special Protection Areas (SPAs), Special Areas of Conservation (SACs), Ramsar sites | 5km | 1% | No upper threshold |
| Sites of Special Scientific Interest (SSSIs) | 5km | 20% | 50% |
| Local nature sites (National Nature Reserves, Local Nature Reserves, Local Wildlife Sites, Ancient Woodlands) |
2km | 100% | 100% |
Results of ammonia screening assessment
The Environment Agency will tell you if you need to submit detailed ammonia modelling after completing their ammonia screening assessment.
You will need to submit detailed modelling if:
- your proposed activities are within 250 metres of any protected conservation site
- ammonia screening assessment shows ammonia emissions from your proposal could affect protected conservation sites
- the original permit for your farm included instructions on how you must reduce ammonia emissions, known as an ‘improvement condition’, and this required you to reduce ammonia emissions at a protected nature conservation site
You will need to do detailed modelling if your ammonia screening result is above the following screening thresholds:
- 1% for SPAs, SACs and Ramsar sites
- 50% for SSSIs
- 100% for local nature sites
If you are within 5 kilometres of a SSSI and your result is between the lower and upper screening thresholds, the Environment Agency will check other permitted farms in the area. If the combined emissions are above the upper threshold, you will need to do detailed modelling.
The Environment Agency revised the standard ammonia emission factors in November 2024. If you need to compare the baseline against the proposal in your detailed modelling assessment, you will need to establish the most appropriate emission factors to provide the lowest baseline impacts. Contact the Environment Agency for further guidance on establishing baselines.
How to do detailed modelling
Detailed modelling uses computer software that models the passage of a substance as it travels through the atmosphere until it reaches the ground.
Detailed modelling requires specialist knowledge. You can find a consultant to do it for you. They’ll charge for their services. Your industry body representative may be able to offer further advice.
For guidance on detailed modelling, see Environmental permitting: air dispersion modelling reports.
Odour and noise management
Odour and noise from the farm may affect receptors such as local residents, schools, hospitals, parks or businesses.
You’ll need to submit written odour and noise management plans as part of your application if:
- there are receptors within 400 metres of the site boundary
- the site has been the cause of odour or noise complaints in the past
Read the comply with your environmental permit guidance to find out what you must do to prevent odour and noise pollution.
Ammonia emissions risk assessment
You must submit a risk assessment of the impact of ammonia emissions from your site if you’re either:
- applying for a new bespoke permit
- applying to change (vary) an existing environmental permit in a way that will cause an increase of ammonia emissions to air from your farm
Factors that could cause an increase of ammonia emissions include:
- an increase in the number of, or change in the type of animals you keep on the farm
- an increase in the amount of manure or slurry you store
- a change to your site’s design or ventilation that could lead to higher ammonia concentrations
- a change to your site’s design or ventilation that could lead to ammonia settling on a nearby receptor, such as residential housing or a protected conservation site
Activities that release ammonia into water
You generally cannot get a permit for activities that result in releasing ammonia into water.
Contact the Environment Agency before starting your application if you expect to release ammonia to water.
Biomass boilers
You need to assess the environmental impact of nitrogen dioxide and particulate emissions if you:
- add a biomass boiler to an existing permitted site
- propose a biomass boiler in plans for a new site
Contact the Environment Agency and ask to speak to your local officer to discuss how to do the assessment.
Poultry farms: when you do not need to do an air emissions assessment for your biomass boiler
You do not need to do an assessment of air emissions if:
- the fuel comes from virgin timber (whole trees and woody parts of trees), clean non-virgin timber (any timber or timber product that has not been treated), straw or miscanthus (also called elephant grass)
- the biomass boiler appliance and its installation complies with standards equivalent to the now closed Renewable Heat Incentive scheme
In addition, the aggregate boiler net rated thermal input must be less than 0.5MWth (megawatt thermal), or it must meet all of the following:
- the aggregate boiler net rated thermal input is less than or equal to 4MWth
- no individual boiler has a net thermal input greater than 1MWth
- the stack height is at least 5 metres above the ground and may need to be higher if there are buildings within 25 metres – the stack must extend above the roof level of any building by at least 1 metre
- there are no receptors within 50 metres of the emission points
If your proposed biomass boiler installation does not meet this criteria, then use the following criteria for pig farms. You will not need to do an air emissions assessment if it meets the pig farm criteria.
Pig farms: when you do not need to do an air emissions assessment for your biomass boiler
You do not need to do an assessment of air emissions if:
- the fuel comes from virgin timber (whole trees and woody parts of trees), clean non-virgin timber (any timber or timber product that has not been treated), straw or miscanthus (also called elephant grass)
- the biomass boiler appliance and its installation complies with standards equivalent to the now closed Renewable Heat Incentive scheme
In addition, the aggregate boiler net rated thermal input must be less than 0.5MWth, or it must meet all of the following:
- the aggregate boiler net rated thermal input is less than 1MWth
- the stack height is greater than 1 metre above the roof level of buildings within 25 metres (where there are no buildings within 25 metres, the stack height must be a minimum of 3 metres above ground)
- there are no SPAs, SACs, Ramsar sites or SSSIs within 500 metres of the emission points
- there are no National Nature Reserves, Local Nature Reserves, Local Wildlife Sites or Ancient Woodlands within 100 metres of the emission points
Where the aggregate boiler net rated thermal input is greater than 1MWth but less than 2MWth, you do not need to do an assessment of air emissions if, in addition to meeting all of the above criteria (including fuel type and compliance with the now closed Renewable Heat Incentive scheme), there are no receptors within 150 metres of the emission points.
Net rated thermal input definition
Net rated thermal input means the rate at which fuel can be burned at the maximum continuous rating of the appliance, multiplied by the net calorific value of the fuel. It’s expressed in MWth. Ask the manufacturer of the biomass boiler for this information.
Dust and bioaerosols
You will need to produce and submit a dust and bioaerosol management plan with your application if there are relevant receptors within 100 metres of your farm, such as the farmhouse or farm worker’s houses.
In your dust and bioaerosol management plan, you must give details of control measures you will use to manage the risks from dust and bioaerosols from your farm. Tables 1 and 2 and checklist 1 and 2 in ‘assessing dust control measures on intensive poultry installations’ explain the methods you should use.
The format of your dust and bioaerosol management plan should be similar to your odour and noise management plan.
Submit your application
Submit your application within 6 months of your ammonia screening assessment to make sure the data remains current.
If your application requires detailed modelling, you must:
- show that your emissions are at the acceptable levels in the screening thresholds table
- provide plans to show how you will reduce them if they’re not
If you’re unable to propose ways to reduce your emissions below these levels, the Environment Agency will do a detailed assessment of your proposal. For SPAs, SACs, Ramsar sites and SSSIs the Environment Agency may consult with Natural England before they decide whether to approve your permit.
For help and advice
Contact the Environment Agency if you have queries.
General enquiries
National Customer Contact Centre
PO Box 544
Rotherham
S60 1BY
Email enquiries@environment-agency.gov.uk
Telephone 03708 506 506
Telephone from outside the UK (Monday to Friday, 8am to 6pm GMT) +44 (0) 114 282 5312
Monday to Friday, 8am to 6pm.
Updates to this page
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Updated guidance on how to request an ammonia screening assessment, which you must do when applying for a new intensive farming permit or applying to vary an existing one which may affect ammonia emissions.
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Updated the ammonia screening sections to clarify how the process works and the values used. A 1% ammonia screening threshold now applies to farms within 5 km of Special Areas of Conversation (SACs), Special Protection Areas (SPAs) and Ramsar sites.
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Linked to updated guidance on the 'ammonia emission factors for pig and poultry screening, modelling and reporting' that the Environment Agency checks against.
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Section 'Ammonia screening thresholds' table: the distance from special protection areas (SPAs), special areas of conservation (SACs) and Ramsar sites to your farm is now 5km.
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Amended to reflect Environment Agency position on the need for an air emissions assessment for biomass boilers. For poultry farms, if the proposed biomass boiler installation does not meet the first set of criteria, then the criteria for the pig farm can be used. An air emissions assessment is not needed if it meets the pig farm criteria.
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First published.