Guide
Control and monitor air emissions
How to comply with air emissions permit conditions for Part A and Part B regulated activities. Covers the difference between Environment Agency and local authority regulation, emission limits, MCERTS monitoring, stack testing, abatement equipment, and reporting requirements.
If your business carries out industrial activities that release pollutants into the air, you are likely to need an environmental permit with conditions controlling what you emit, how you monitor emissions, and how you report to your regulator.
The type of permit you need and who regulates you depends on the scale and nature of your activity. Getting this wrong can result in criminal prosecution, unlimited fines, and enforcement action including suspension of operations.
Which regulator controls your emissions
In England and Wales, industrial activities that produce emissions are classified into three categories under the Environmental Permitting (England and Wales) Regulations 2016. The category determines your regulator:
Part A(1) - Environment Agency regulated
The most potentially polluting activities, including large combustion plants, oil refineries, chemical manufacturing, waste incineration, and metals processing. The Environment Agency (or Natural Resources Wales) regulates emissions to air, water, and land through an integrated environmental permit.
Part A(2) - Local authority regulated (LA-IPPC)
Medium-scale industrial activities regulated by your local authority under Local Authority Integrated Pollution Prevention and Control. These permits control emissions to air, water, and land.
Part B - Local authority regulated (LAPPC)
Activities that primarily cause emissions to air only. Your local authority regulates these under Local Air Pollution Prevention and Control (LAPPC). Common Part B activities include:
- Vehicle respraying and paint application
- Timber and furniture manufacturing
- Petrol vapour recovery (fuel storage and unloading)
- Dry cleaning using solvents
- Cement batching
- Coating and printing processes
- Foundries and metalwork below Part A thresholds
- Crematoria
The full list of regulated activities is set out in Schedule 1 to the Environmental Permitting Regulations 2016.
Emission limits in your permit
Your permit sets specific emission limit values (ELVs) for the pollutants your activity releases. These are legally binding conditions. Common pollutants with limits include:
- Particulate matter (PM10, PM2.5) - dust, smoke, and fine particles
- Nitrogen oxides (NOx) - from combustion processes
- Sulphur dioxide (SO2) - from burning sulphur-containing fuels
- Volatile organic compounds (VOCs) - from solvents, paints, and coatings
- Carbon monoxide (CO) - from incomplete combustion
- Heavy metals - from metalworking and waste treatment
ELVs are expressed as concentrations (mg/m3) or mass emission rates (kg/hour or tonnes/year). Your permit specifies which format applies. Exceeding any limit is a permit breach and must be reported to your regulator immediately.
Best available techniques (BAT)
Permit conditions are based on best available techniques for your sector. BAT reference documents (BREFs) and process guidance notes describe the techniques and emission levels your regulator expects. You must demonstrate you are using BAT to control emissions.
Monitoring your emissions
Your permit specifies what monitoring you must carry out and how frequently. There are two main approaches:
Continuous emissions monitoring systems (CEMS)
Large Part A installations often require continuous monitoring of key pollutants using automated instruments fitted to the stack. CEMS must be:
- Certified under the MCERTS scheme (the Environment Agency's Monitoring Certification Scheme)
- Calibrated and quality-assured in accordance with EN 14181
- Subject to regular annual surveillance testing
Periodic stack testing (manual monitoring)
Most Part B activities and smaller Part A installations require periodic stack emission testing rather than continuous monitoring. Testing must be carried out by an MCERTS-accredited organisation to ensure results meet regulatory standards.
Typical testing frequencies are:
- Annual for most regulated pollutants
- More frequently if your regulator has concerns about compliance
- After significant changes to plant, fuel, or operating conditions
Stack tests measure pollutant concentrations and flow rates from the chimney or vent. Results are compared against your permit limits. You must keep test reports and make them available to your regulator on request.
MCERTS requirements
The Environment Agency's Monitoring Certification Scheme (MCERTS) sets quality standards for emissions monitoring. Under MCERTS:
- Monitoring equipment must be MCERTS-certified
- Laboratories analysing stack samples must be MCERTS-accredited
- Organisations carrying out manual stack testing must hold MCERTS accreditation
- Individual technicians need MCERTS competence certification
Using non-MCERTS methods without prior written agreement from your regulator may mean your monitoring results are not accepted for compliance assessment.
Abatement equipment
If your raw emissions exceed permit limits, you need abatement equipment to reduce pollutant concentrations before they leave the stack. Common types include:
- Bag filters and cyclones - for particulate removal
- Scrubbers (wet or dry) - for acid gases and SO2
- Activated carbon adsorption - for VOCs and organic compounds
- Selective catalytic reduction (SCR) - for NOx reduction
- Thermal and catalytic oxidisers - for destroying VOCs
Your permit may specify which abatement techniques to use. You must maintain abatement equipment in good working order at all times. Equipment failures must be reported to your regulator and may require you to reduce or stop operations until the equipment is repaired.
Reporting requirements
All permit holders must report to their regulator. Requirements vary by permit type:
Part B (LAPPC) reporting
- Submit monitoring results as specified in your permit (typically annually)
- Report any breaches of emission limits within 24 hours
- Notify your local authority of changes to plant, processes, or operating hours
- Keep records of operating hours, raw materials used, and abatement equipment maintenance
Part A reporting
- Submit annual monitoring reports to the Environment Agency or NRW
- Report breaches immediately and follow up in writing
- Some sites must report to the UK Pollutant Release and Transfer Register (PRTR)
- Large combustion plants have additional reporting under the Industrial Emissions Directive (retained in UK law)
Inspections and enforcement
Your regulator will inspect your premises, sometimes without prior notice. Inspectors can:
- Enter your premises at any reasonable time
- Take samples and measurements
- Inspect and copy records
- Require you to provide information
- Seize equipment or materials if there is a risk of serious pollution
Obstruction of an inspector is a criminal offence.
If enforcement action is taken, your regulator may issue:
- Compliance notice - requiring you to take specific steps by a deadline
- Enforcement notice - requiring corrective action for permit breaches
- Suspension notice - stopping operations until issues are resolved
- Revocation notice - withdrawing your permit entirely
- Prosecution - for serious or repeated breaches, carrying unlimited fines and potential imprisonment
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1. Check whether your activity is regulated
Review Schedule 1 of the Environmental Permitting Regulations 2016 (or equivalent devolved legislation) to determine if your activity is classified as Part A(1), Part A(2), or Part B. Contact your local authority environmental health team if unsure.
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2. Apply for the correct permit
For Part A(1) activities, apply to the Environment Agency (or NRW). For Part A(2) and Part B activities, apply to your local authority. Include details of your processes, emission sources, proposed abatement, and monitoring arrangements.
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3. Install monitoring equipment to MCERTS standards
Ensure all continuous monitoring systems are MCERTS-certified. For periodic testing, engage an MCERTS-accredited monitoring organisation. Install appropriate sample points on stacks and vents.
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4. Install and maintain abatement equipment
Fit appropriate abatement technology to meet your permit emission limits. Maintain equipment according to manufacturer specifications and keep maintenance logs.
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5. Carry out monitoring as specified in your permit
Conduct stack testing or continuous monitoring at the frequencies your permit requires. Use MCERTS-accredited methods and laboratories. Keep all results on file.
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6. Report to your regulator
Submit monitoring results at the frequency specified in your permit. Report any emission limit breaches immediately (within 24 hours) and follow up in writing. Notify your regulator of any changes to plant or processes.
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7. Prepare for inspections
Keep records of operating hours, raw materials, abatement maintenance, and monitoring results readily accessible. Ensure staff understand their obligations and can explain operations to inspectors.