Guidance

Crematoria: emissions limits, monitoring and other provisions

Published 4 December 2025

This document is part of the crematoria technical guidance. There are 4 more documents that cover this topic.

Read all the documents to make sure you have the information you need.

Operational controls 

Control over the combustion conditions is of fundamental importance in preventing and controlling emissions to air. 

The key controls over the combustion conditions are the: 

• combustion temperature  
• residence time of the combustion gases in the secondary combustion chamber  
• concentration of carbon monoxide and excess oxygen at the exit of the secondary combustion chamber 

Residence time in the secondary combustion chamber shall be demonstrated by calculation at the design stage and verified at commissioning. Verification may require the temporary installation of additional thermocouples. The residence time requirement should be verified at the operating temperature of the secondary combustion chamber and that temperature must exceed the values set out below. 

Table 2: Operating limits and targets 

Substance or parameter	Operating limit	Cremator type	Averaging period
Carbon monoxide	Less than 100 mg per Nm3	All	As an average concentration between 2 minutes and 62 minutes from the start of each cremation
Oxygen content at exit of secondary combustion chamber	Minimum of 6% volume per volume	All	As an average concentration between 2 minutes and 62 minutes from the start of each cremation. For small-scale cremators, the averaging period will be between 2 and 32 minutes as the cremation time will be shorter
Oxygen content at exit of secondary combustion chamber	Minimum of 3% volume per volume	All	5 minute averages throughout the whole of each cremation
Temperature of secondary combustion chamber	Minimum of 850˚C	Unabated cremators	5 minute averages throughout the whole of each cremation
Temperature of secondary combustion chamber	Minimum of 800˚C (or in the event of flue gas treatment equipment failure, the minimum temperature must be increased to 850˚C)	All except unabated cremators	5 minute averages throughout the whole of each cremation
Residence time of secondary combustion chamber without correction for temperature, oxygen, or water vapour	Minimum of 2 seconds	All	5 minute averages throughout the whole of each cremation

Carbon monoxide targets  

The operating limit for carbon monoxide in this table is a performance target, not an emission limit value. Carbon monoxide (CO) measurement should ideally be made at the exit of the secondary combustion chamber. Modification to existing cremators is not required. 

Oxygen limits  

Oxygen concentration can be measured wet or dry. 

Authorising different conditions for cremators fitted with flue gas treatment

Cremators fitted with flue gas treatment may have different conditions authorised than those set out in Table 2 for:  

• temperature  
• residence time  
• oxygen content at the exit of the secondary combustion chamber  

Regulators may authorise different conditions if all the other requirements of this guidance are met, including all emission limit values. The regulator will then specify the conditions in the permit. The frequency of dioxin monitoring (Table 4) will be increased to annual in all such circumstances. 

Modifying cremators and other features  

Modifying secondary combustion chamber convolutions 

When re-bricking a cremator, the convolutions of the secondary combustion chamber should be maintained. If it is changed or modified to impact the original design, the volume of the chamber shall be recalculated and reverified. 

Using automated shutdown 

Some cremators are fitted with an automated shutdown feature so that the last cremation of the working day can be completed unsupervised.  

Engaging this function carries a degree of risk that equipment malfunction or unexpected difficulties with the cremation could occur during this period. If using this feature the operator must be satisfied that the cremation has proceeded to a point where this risk is minimal, such as when the cremation has reached the calcination stage. 

Monitoring emissions  

Emissions of the substances listed in Tables 3 and 4 must, where relevant, be controlled. The emission limit values and provisions described in this section are achievable using the guidance document for crematoria: best available techniques.

Operators must monitor emissions using the standard specified in the guidance below or an equivalent method agreed by the regulator.  

Whilst there are no emission limits for nitrogen oxides or mercury emissions from unabated cremators, operators must: 

• make measurements of these emissions  
• report these emissions to the regulator  
• provide emissions data for these substances, such as for local air quality purposes 
• provide data for future guidance reviews 

Where reference is made to a British, European, or International Standard (BS, CEN or ISO) in this section, the standards referred to are correct at the date of publication. 

Always check the standards because they are periodically amended and updated. 

You can find more information on monitoring in the Environment Agency guidance on: 

• monitoring stack emissions: measurement locations 
• monitoring stack emissions: techniques and standards for periodic monitoring 

Continuous emission monitoring 

Table 3: Emission monitoring standards for continuous monitoring 

Substance or parameter	Standards	Calibration standards
Particulate matter (applies to unabated cremators only)	EN 15859	EN 17389
Carbon monoxide	EN 15058, EN 14789	EN 17389
Oxygen	EN 15058, EN 14789	EN 17389
Temperature	Calibration shall be traceable to national standards	Calibration shall be traceable to national standards

You must carry out instrument calibration before taking measurements. This should be done by making parallel measurements using the relevant reference methods at least once a year. You must inform the regulator about the results. 

For crematoria with flue gas treatment, the operator must install a filter leak detection device that will operate continuously. The instrument will detect filter leaks that would be likely to lead to an exceedance of the particulate matter emission limit value. 

Requirements for continuous monitoring 

Where continuous monitoring is required for any substance or parameter, it should be carried out as follows: 

• all continuous monitoring readings should be on display to appropriately trained operating staff 
• instruments should be fitted with a visual alarm to warn the operator of abatement equipment failure or instrument malfunction 
• regulators should decide whether additionally to specify an audible alarm, having regard to, amongst other things, the likelihood of the visual alarm not being noticed, and the intrusiveness of any such alarm for those using the crematorium 
• the activation of alarms should be automatically recorded 

Periodic emission monitoring  

Table 4: Emission monitoring frequencies and standards for periodic monitoring 

Substance or parameter	Standards	Minimum monitoring frequency
Particulate matter	EN 13284-1	Once every year
Dioxins and furans (PCDD/F)	EN 1948, Parts 1, 2 and 3	Once every 3 years. Once every year for unabated cremators and cremators using operating conditions different to those in Table 2. The first measurement for a new cremator should be in the first 12 months of operation
Mercury	EN 13211	Once every year
Hydrogen chloride (HCl)	EN 1911	Once every year
Total organic carbon (TOC)	EN 12619	Once every year
Oxides of Nitrogen NOX (NO and NO2 expressed as NO2)	EN 14792	Once every year from 1 month after publication
Ammonia (NH3) to measure ammonia slip associated with the selective non-catalytic reduction (SNCR) process. So, this only applies where NOx abatement is installed	EN ISO 21877	Once every year from 1 month after publication

Deviation from a monitoring standard 

Where monitoring is not in accordance with the main requirements of the relevant standard, operators must report deviations from the standard as well as an estimation of any error invoked. 

Monitoring equipment and techniques  

From 1 month after publication, monitoring equipment, techniques, personnel, and organisations employed for the emissions monitoring programme shall be accredited to EN ISO/IEC 17025. In England and Wales, accreditation to the Environment Agency’s Monitoring Certification Scheme (MCERTs) will show this accreditation. 

The regulator may require more frequent monitoring than that set out in Table 4 or continuous monitoring, based on the impact of emissions on local air quality or other sensitive receptors.

Sampling 

Whether sampling on a continuous or non-continuous basis, care is needed in the design and location of sampling systems to ensure representative samples for all emissions. This means that: 

• sampling points on new crematoria should be designed to comply with the relevant standards in the guidance on monitoring stack emissions: measurement locations 
• the operator should ensure that stacks or ducts are fitted with facilities for sampling that allow compliance with the sampling standards 

If it’s not possible (for example, in older cremators which were designed to fit into an existing building) operators must report:  

• deviations from the standard   
• an estimation of the increased uncertainty in the monitoring results 

A safe and permanent means of access to the test ports shall be provided, to enable the sampling and monitoring specified in Table 4 to be carried out. 

Sampling for polychlorinated dibenzo dioxins and furans  

When sampling for polychlorinated dibenzo dioxins and furans, it may be impossible for the sampling point to be located where the temperature of the flue gases is below 200°C and remains so until discharge to atmosphere (such as in an unabated cremator). This means it is outside the temperature range where reformation or de novo synthesis takes place. 

In this case, the operator should notify the regulator of the minimum temperature at which the measurement can practically be made, and the reason why this cannot be below 200°C before sampling takes place. 

Emission limit values 

All activities shall comply with the emission limits in Tables 5 and 6. 

The reference conditions for emission limits are: 273.1K, 101.3kPa, 11% oxygen v/v, dry gas unless otherwise stated. 

Compliance will be assessed using an average value of 3 consecutive measurements of 60 minutes each, as described below unless otherwise stated. 

Cremation is a batch process as described in the guidance document for crematoria: process, types of fuels and flue gas treatment.   

Emissions monitoring for compliance purposes should only occur during adult cremation.  

Compliance not standardised across all cremators 

A common reference is needed for compliance monitoring across all types of cremators. The initial stage has too short a duration for sampling of emissions. It is also not practical to sample emissions during the ashing phase, as the turbulence caused by the open ash door may bias the results.  

For cremators with flue gas treatment, the emissions will be strongly influenced by the performance of the abatement equipment. Therefore, for these cremators, emission limits are set on a concentration basis only.  

For unabated cremators, emission limits for some substances have an alternative mass release limit, which are meant to be broadly equivalent.  

Monitoring periods 

Emissions are expected to peak during the first hour of the process. A common reference of one hour starting approximately 2 minutes following the closure of the cremator door is used for unabated cremations and cremations where the flue gas treatment system serves a single cremator. 

Where 2 or 3 cremators are served by a common flue gas treatment system, it is not possible to set the emissions monitoring period as described above, because each cremator is likely to be at a different part of the process. In such cases, the monitoring period should coincide with the start of cremation in one of the units with the operating status of the other units carefully recorded. The other units should operate as normal during this period. 

Emissions monitoring should commence as soon as a stable air flow is established following closure of the cremator door. Typically, this will be 2 minutes into the cremation process. Emissions monitoring shall then continue for a period of one hour.  

Invalid tests 

For unabated cremators, the test will be invalid and must be done again if:  

• the coffin is breached before emissions monitoring begins 
• the cremation is completed (other than ashing) within one hour from the start of monitoring  

For cremators with flue gas treatment, the test will be invalid and must be done again if any cremator connected to the flue gas treatment system ceases operation during the monitoring period. 

Table 5: Emission limit values for unabated cremators 

Substance	Emission limit value	Averaging period
Particulate matter	80mg per Nm3 or 120g	As an average concentration between 2 minutes and 62 minutes from the start of each cremation or as a total mass emission over the same time period
HCl	60mg per Nm3 or 100g	As an average concentration between 2 minutes and 62 minutes from the start of each cremation or as a total mass emission over the same time period
TOC	20mg per Nm3	As an average concentration between 2 minutes and 62 minutes from the start of each cremation
NOX (NO and NO2 as NO2)	No limit applies	As an average concentration between 2 minutes and 62 minutes from the start of each cremation
Mercury	No limit applies	As an average concentration over 3 cremations between 2 minutes and 62 minutes from the start of each cremation
PCDD/F	1ng per Nm3 or 4.5μg	As an average concentration over 3 cremations between 2 minutes and 62 minutes from the start of each cremation or as a total mass emission over the same period. A longer monitoring period may be needed where emissions are very low, and the monitoring uncertainty is high as a proportion of the measured value

Where an emission limit value is expressed both as a concentration or a mass, the operator chooses whether the mass or the concentration limits apply, and the regulator should then specify those limits in the permit.

Table 6: Emission limit values for all other cremators 

Substance	Emission limit value	Applies to existing or new cremators
Particulate matter	10mg per Nm3	Existing
Particulate matter	5mg per Nm3	New
Hydrogen chloride (HCl)	30mg per Nm3	Existing
Hydrogen chloride (HCl)	20mg per Nm3	New
Total organic carbon (TOC)	20mg per Nm3	Existing
Total organic carbon (TOC)	10mg per Nm3	New
Oxides of Nitrogen NOx (NO and NO2 as NO2)	200mg per Nm3	All from 4 years after publication
Ammonia (NH3). To measure ammonia slip associated with the SNCR process. So, this only applies where NOx abatement is installed	No limit applies	All
Mercury	50μg per Nm3	Existing
Mercury	30μg per Nm3	New
PCDD/F	0.1ng per Nm3	All

Apart from PCDD/F, which will need a longer monitoring period, the averaging period for all substances, must be an average concentration over 3 periods of 60 minutes. The length of the monitoring period for PCDD/F should reflect the expected emission level and the level of the monitoring uncertainty.  

Dilution air 

Dilution air may be added for waste gas cooling or improved dispersion where this is shown to be necessary because of the operational constraints of the crematoria. Dilution air should have no effect on the assessment of compliance with emission limit values. 

Cremulation (processing bone fragments or remains after cremation) 

For all cremators, the remains in the cremator should only be moved when calcination is completed. 

Particular care is needed in the removal of ash and non-combustible residues from an unabated cremator to prevent dust emissions via the flue. 

Cremated remains should be moved and allowed to cool before they are processed in the cremulator (ash processor). Processed remains must be stored in a covered container. 

If an automated shutdown process is used at the end of a working day, this will take place at the start of the next working day. 

Cremulators must be fitted with suitable exhaust filters and a gross filter failure detection device, such as differential pressure measurement. This must operate continuously when the cremulator is in use.  

Particulate emissions from cremulators equipped with a detection device should be insignificant and may be vented internally or externally, no emission limits apply. 

Chimney or stack height emissions 

Pollutants emitted via a chimney or stack require sufficient dispersion and dilution in the atmosphere to ensure that the resultant ground level concentrations are acceptable in terms of their impact on health and environment. 

Historically, stack heights have been calculated using Her Majesty’s Inspectorate of Pollution (HMIP) Technical Guidance Note (Dispersion) D1. However, this dates from 1993 and so is 30 years old. In any event, D1 should be viewed as a dated methodology for calculating stack height. It is not a method for assessing pollutant dispersion and its effects on ambient air quality. 

Whatever method is used to determine the stack height (and efflux velocity), an assessment of the impact of emissions on local ambient air quality shall be carried out. For new crematoria, this should form part of the permit application. For existing crematoria, this should be done at permit review. 

Assessing the impact of emissions to air 

To assess the impact of your emissions on local ambient air quality, you should use assessment tools such as the Environment Agency’s H1 software tool or air dispersion modelling. 

The H1 software tool is a simplified modelling tool which uses a precautionary approach to calculate a predicted maximum ground level pollutant concentration. It can be used to screen out emissions which are insignificant. 

Process Contributions 

To screen out a substance so that you do not need to do any further assessment of it, the Process Contribution (PC) must meet both of the following criteria: 

• the short term PC is less than 10% of the short term environmental standard 
• the long term PC is less than 1% of the long term environmental standard 

If you meet both criteria no further assessment of the substance is required. 

Where this is not the case, a more detailed assessment of those pollutants will be necessary. This will include the use of background data to determine the Predicted Environmental Concentration (PEC) and could include the use of more sophisticated air dispersion modelling.  

Assessments should ordinarily be carried out on the basis that emissions to air are at the maximum permitted level. Where there are no emission limit values (ELVs) in place emissions monitoring data can be used. 

In circumstances where 2 or 3 cremators discharge through a common chimney, the assessment should be based on the operating scenario which results in the highest predicted ground level concentrations. 

Reducing the impact of stack and chimney emissions 

Previous versions of the crematoria guidance have not included any reference to emissions of nitrogen oxides. As a result, it is likely that the dispersion of NOX emissions was not considered when designing the stack height of existing crematoria. 

Where necessary, regulators may need to reduce the emission limit values (in Tables 5 and 6) for existing crematoria to ensure the impact is acceptable. For new crematoria, the stack height may be increased to ensure the impact is acceptable. 

Emergency release vents 

For crematoria with flue gas treatment, each treatment unit can have one flue plus an emergency release vent (ERV) for each cremator connected to the system. As the ERV should only be used very infrequently, an air quality impact assessment of the ERV is not needed if the ERV stack is at least the same height as the main stack or greater. 

Exit velocity 

The exit (efflux) velocity from the stack must be sufficient to prevent aerodynamic downwash of the discharge plume. Dispersion modelling may be used to justify the efflux velocity under normal operating conditions.  

Do not use a cap or other restriction at the stack exit. This will ensure dispersion is not impaired by either low exit velocity at the point of discharge, or deflection of the discharge. However, a cone may sometimes be useful to increase the exit velocity to achieve greater dispersion.  

Insulation 

Liquid condensation on internal surfaces of stacks and exhaust ducts might lead to corrosion and ductwork failure or to droplet emission. Adequate insulation will minimise the cooling of waste gases and prevent liquid condensation by keeping the temperature of the exhaust gases above the dewpoint.  

A leak in a stack or vent and the associated ductwork, or a build-up of material on the internal surfaces may affect dispersion. Flues and ductwork should be cleaned to prevent the accumulation of materials, as part of the routine maintenance programme. 

Visible and odorous emissions 

Emissions from cremators should give off visible smoke when they are in normal operation. All releases to air should be free from persistent visible emissions, other than condensed water vapour. All releases to air should be free from droplets.  

There should be no odorous emissions smelt by the regulator. 

In other than normal operation, the operator should make periodic visual and olfactory assessments of emissions, including at the start of and during a cremation cycle. The operator should record the location and result of the assessment in the log.  

Reducing energy consumption and carbon emissions 

This guidance does not include emission or statutory compliance requirements relating to the reduction or elimination of carbon emissions from this sector. However, operators in the public and private sectors are already committed to carbon reduction as part of local authority or company policy.

Carbon emissions at crematoria arise from fuel and electricity use. They also arise from the combustion of the coffin (including fittings).

Operators that make voluntary commitments to reduce their carbon emissions may consider reductions through improved energy efficiency by utilising a combination of strategies relating to the following:

• use of electrical cremators in combination with decarbonisation of the electricity supply has the potential to reduce carbon emissions at crematoria
• replacement of fossil fuels with sustainable biofuels will also reduce carbon emissions, depending on the accounting methodologies used
• use of hydrogen as an alternative to gas and other fossil fuels

Carbon reduction may also come from other parts of the funeral sector in the form of innovation and use of materials that are more sustainable.

Evaluating carbon emissions 

Operators that decide to track and evaluate their carbon consumption may wish to consider the following approach to quantification as a starting point.

Operators are advised to collect data on fuel and electricity consumption for each cremator (including all abatement equipment). If there is more than one cremator operating with a shared flue gas treatment system, operators must measure fuel and electricity consumption for the whole system. 

Operators estimating carbon consumption would also need to be supported by a calculation methodology that references relevant sources of data, including emission factors. Emissions could then be reported as both total mass emissions (kg) and the average mass of emissions per cremation.

Calculating emissions 

Operators seeking to accurately evaluate their carbon emissions may wish to install equipment-specific metering for gas and electricity supplies.

Fuel and electricity consumption can then be converted into carbon dioxide emissions using standard publicly available greenhouse gas conversion emission factors. Carbon intensity data is available for different fuels used. Data is also available for electricity drawn from the national grid. Carbon intensity data on electricity is updated from time to time. 

Further work is needed on developing emission factors for N2O emissions, so these should be excluded from calculations at the present time.

Consumables and waste materials 

Waste residues collected from inside the flue gas treatment equipment must be disposed of in accordance with waste legislation. 

Dusty materials, dusty wastes and wastes containing mercury must be contained. 

Operators must keep records of all wastes sent for recycling or disposal. Specifically, a record must be kept of the consumption of flue gas treatment reagents. 

Reporting and notifications 

Good communication between the crematoria operator and their regulator is essential for an effectively regulated facility. 

The operator must keep records of all inspections, tests, monitoring and visual assessments. The records should be: 

• kept on site 
• kept by the operator for at least two years 
• made available for the regulator to examine on request 

If any records are kept off-site, they must be made available for inspection within one working week of any request by the regulator. 

Reporting periodic emissions monitoring 

If an operator intends to carry out periodic emissions monitoring, they must notify the regulator in sufficient time (typically 14 to 21 days) so that they can decide whether to observe the testing. 

The operator should submit the results of all periodic emissions testing to their regulator within a timescale and format agreed with the regulator. This should be no more than 8 weeks from the date of the test, except if there is a non-compliance. 

The Department for Environment, Food & Rural Affairs (DEFRA) will produce a recommended format for local authority regulators in England to use. 

Reporting operational monitoring data 

The operator must also report operational monitoring data within a timescale, frequency and format agreed with the regulator. These reports must include the: 

• number of occasions on which an operating limit has not been achieved for any parameter in that table  
• recorded values of all substances and parameters listed in Table 2 for each of those occasions 

These operational limits and targets are listed in Table 2. 

Non-compliance of ELVs 

The operator must restore compliance in the shortest possible time, in the event of any: 

• non-compliance with any emission limit value 
• malfunctions and breakdown of the plant that leads to abnormal operating conditions, such as operation of the flue gas treatment bypass 
• complaints about odour or smoke 

To restore compliance, the operator must: 

• notify their regulator within 24 hours of receiving the information 
• agree the investigation of the issue with their regulator 
• undertake the agreed investigation 
• adjust the process or activity to minimise those emissions 
• if applicable, re-test to demonstrate compliance as soon as possible 
• promptly record the events and actions taken 
• submit to the regulator, reports and updates as agreed 

Failure of flue gas treatment equipment 

Emergency relief vents (ERV) or bypass systems should not normally be used when cremation is underway, or during maintenance. The ERV or bypass should only be used either: 

• when the heat removal equipment has failed, and the equipment would otherwise be damaged 
• during start up and shutdown 
• due to short term power interruptions 

If there is a failure of the heat removal equipment during a cremation, that cremation must be completed operating in bypass mode.  

Similarly, if there is an equipment malfunction which does not trigger the ERV or bypass system during a cremation, that cremation must be completed.  

Until the failed system is repaired, the cremator may continue to be operated in bypass mode, provided that: 

• it can meet all the operational standards for an unabated cremator 
• the period of such operation does not exceed 100 hours in any calendar year, without the prior agreement of the regulator 

Otherwise, the cremator should not be used until the failed system is repaired. 

In unusual and unexpected circumstances, where the use of an ERV is likely to exceed 100 hours, an assessment of the impact on local ambient air quality must be made before the 100-hour limit is reached. 

The number of hours operating in bypass mode must be reported to the regulator.

This document is part of the crematoria technical guidance.

Next: Crematoria: best available techniques (BAT)