Guidance

Monitoring stack emissions: techniques and standards for periodic monitoring

Updated 17 November 2022

We have structured this index to help you choose an appropriate periodic monitoring technique and standard.

Standards may contain various options and approaches.

We have produced method implementation documents (MIDs) for several standards to make sure they are applied consistently.

If a MID has been produced we have included it in the index, next to the relevant standard.

Substances are listed in alphabetical order.

1. Aldehydes (excluding formaldehyde)

Here are the monitoring techniques and standards.

1.1 Monitoring technique 1

Monitoring technique 1 is extractive sampling onto sorbent tube, with subsequent extraction and analysis.

Moisture may restrict the use of a sorbent tube method. Under these circumstances you may adapt an impinger method, such as CEN TS 17638.

Monitoring standard

The relevant monitoring standards are:

• European committee for standardisation technical specification CEN TS 13649 for sampling
• National Institute of Occupational Safety and Health (NIOSH) 2016 for analysis
• NIOSH 2539 for aldehyde screening

1.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a portable Fourier-transform infrared spectroscopy (FTIR) analyser.

Monitoring standard

The relevant monitoring standard is CEN TS 17337.

The following applies to all determinands measured when using CEN TS 17337:

• you do not have to do an on-site response test but you must do an annual response test on the longest heated line used and for each analyser used
• you may do an entire system check instead of a direct to analyser check and losses and leakage sample line check – you must use a pass criteria of 5% or less of the certified check gas value
• if a determinand, with the exception of volatile organic compounds (VOCs), is on a flexible scope, it must be verified (called validation in CEN TS 17337) every 4 years – you must do this annually on all determinands measured for compliance monitoring
• for VOCs an annual verification may be carried out on a sub-set of the VOCs that are on a flexible scope

2. Amines and amides

Here are the relevant monitoring techniques and standards.

2.1 Monitoring technique 1

Monitoring technique 1 is non-isokinetic sampling, collection on silica gel tubes and analysis by gas chromatography.

This technique measures aromatic and aliphatic amines.

The stack gas must be dried before reaching the silica gel tubes.

If droplets are present you need carry out isokinetic sampling and adapt an impinger method, such as EN ISO 21877.

Monitoring standard

The relevant monitoring standards are:

• CEN TS 13649 for sampling
• NIOSH 2002 and NIOSH 2010 for analysis

2.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and FTIR analyser. This technique is able to analyse specific amines.

Monitoring standard

The relevant monitoring standard is CEN TS 17337.

3. Ammonia

Here are the relevant monitoring techniques and standards.

3.1 Monitoring technique 1

Monitoring technique 1 is non-isokinetic or isokinetic sampling and impingement into dilute sulfuric acid. Analysis is by spectrophotometry, flow analysis and spectrometric detection or ion chromatography.

Isokinetic sampling is required if droplets are present.

Monitoring standard

The relevant monitoring standard is European and International Standard EN ISO 21877.

If there is potential for biological activity in the samples you must keep them at a temperature below 5°C. Typically samples from combustion processes will not have the potential for biological activity, so storage below 5°C is not required.

3.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and FTIR analyser.

Monitoring standard

The relevant monitoring standard is CEN TS 17337.

4. Arsine (also known as arsane)

Here are the relevant monitoring techniques and standards.

4.1 Monitoring technique

Monitoring technique 1 is extractive sampling onto a sorbent tube with subsequent solvent extraction and analysis.

Monitoring standard

The relevant monitoring standards are:

• the procedural requirements of CEN TS 13649 for sampling
• NIOSH 6001 for analysis

The NIOSH method uses the same sorbent tube material as CEN TS 13649 (a solid sorbent tube made of coconut shell charcoal).

5. Benzene

See volatile organic carbons.

6. Bioaerosols

Here are the relevant monitoring techniques and standards.

6.1 Monitoring technique

The monitoring technique is isokinetic sampling and impingement into saline solution. Analysis is by serial dilution and cultivation onto agar plates, followed by counting visually recognisable colonies after cultivation.

Monitoring standard

The relevant monitoring standard is EN 17359.

You may add an additional impinger for processes with elevated moisture levels. If necessary you can filter the impinger and rinse solution before analysis so that the limit of detection is reduced.

A field blank is satisfactory if the agar plate value is not greater than 3 colony forming units per agar plate count.

You can apply the following uncertainty values:

• 30% for total bacteria onto half strength nutrient agar
• 23% for Aspergillus fumigates cultured onto malt extract agar

The culture and enumeration of samples must be carried out in accordance with the guidance in M9 environmental monitoring of bioaerosols at regulated facilities.

7. Biomass (biogenic) and fossil derived carbon dioxide (ratio)

Here are the relevant monitoring techniques and standards.

7.1 Monitoring technique 1

Monitoring technique 1 is absorption of carbon dioxide in liquid and solid alkaline media, or collection of gas in gas bags, canisters or gas bottles. Analysis is by accelerator mass spectrometry, beta-ionization or liquid scintillation.

This technique determines the ratio of biomass and fossil derived carbon dioxide in the carbon dioxide from stack gases.

Monitoring standard

The relevant monitoring standard is EN ISO 13833.

7.2 Monitoring technique 2

Monitoring technique 2 uses a mathematical model based on stack gas and fuel composition. It determines the biogenic fraction in carbon dioxide in stack gas. You use this method when:

• you know the elementary composition of moisture, ash free biomass and fossil matter in the fuel used
• online stack gas composition measurements (oxygen and carbon dioxide) are available at a high accuracy

Online modelling of the biomass fossil ratio enables you to control and report the biomass ratio. You can verify the generated model data using radiocarbon (14C) determined biomass fuel ratio. The results are complementary to the results obtained with ISO 13833.

Monitoring standard

The relevant monitoring standard is ISO 18466.

8. Carbon dioxide

Here are the relevant monitoring techniques and standards.

8.1 Monitoring technique 1

Monitoring technique 1 is a non-dispersive infrared (NDIR) analyser.

Monitoring standard

The relevant monitoring standard is CEN TS 17405.

8.2 Monitoring technique 2

Monitoring technique 2 is a FTIR analyser.

Monitoring standard

The relevant monitoring standard is CEN TS 17337.

9. Carbon monoxide

Here are the relevant monitoring techniques and standards.

9.1 Monitoring technique 1

Monitoring technique 1 is extractive sampling and a NDIR analyser.

Monitoring standard

The relevant monitoring standard is EN 15058.

9.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and FTIR analyser.

EN 15058 is the standard reference method. You may use an alternative method, provided you meet the requirements specified in the MCERTS performance standard for stack emissions monitoring organisations.

Monitoring standard

The relevant monitoring standards are:

• CEN TS 17337
• alternative method for EN 15058

10. Carbon disulfide

Here are the relevant monitoring techniques and standards.

10.1 Monitoring technique 1

Monitoring technique 1 is non-isokinetic sampling and collection on charcoal sorbent tube with subsequent extraction and analysis.

You will need a drying tube as water vapour may cause interference.

Monitoring standard

The relevant monitoring standards are:

• the procedural requirements of CEN TS 13649 for sampling
• NIOSH 1600 for analysis

10.2 Monitoring technique 2

Monitoring technique 2 is using a portable gas chromatograph with an appropriate detector.

Monitoring standard

The relevant monitoring standard is US EPA method 15.

11. Carbonyl sulfide

Here are the relevant monitoring techniques and standards.

11.1 Monitoring technique 1

Monitoring technique 1 is a portable gas chromatograph with an appropriate detector.

Monitoring standard

The relevant monitoring standard is US EPA method 15.

11.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a FTIR analyser.

Monitoring standard

The monitoring standard is CEN TS 17337.

12. Carboxylic acids

Here are the relevant monitoring techniques and standards.

12.1 Monitoring technique 1

Monitoring technique 1 is extractive sampling onto carbon sorbent with subsequent extraction and analysis.

This technique is for acetic acid only. For other carboxylic acids, use appropriate occupational hygiene or health and safety methods.

Monitoring standard

The relevant monitoring standards are:

• CEN TS 13649 for sampling
• NIOSH 1603 for analysis

12.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a FTIR analyser.

This technique is used to measure carboxylic acids, such as:

• methanoic acid (formic)
• ethanoic acid (acetic)
• propanoic acid (propionic)
• acrylic acid (prop-2-enoic)

Monitoring standard

The monitoring standard is CEN TS 17337.

13. Chlorine dioxide

See halogens and halides.

Halogens and halides can be included with chlorine when using a wet chemical analysis method.

14. Chlorofluorocarbons

See VOCs (speciated).

15. Chromium (VI)

15.1 Monitoring technique

The monitoring technique is isokinetic sampling of gas through a filter and absorber solutions. Analysis is by ion chromatography.

Monitoring standard

The monitoring standard is US EPA method 0061.

It was developed for incineration plants but it may be applied to other processes, such as those that produce ferro-alloys.

The standard refers to US EPA M7199 for additional requirements on sample transport, storage, preparation and analysis. Samples must be transported and stored at less than 5°C.

You may use other analysis methods such as colorimetry provided you specify the impinger reagent used.

You can determine hexavalent chromium in fine particulate matter (PM₁₀ fraction) by using EN ISO 23210 (particulate matter size fractionation). You can analyse the PM₁₀ fraction collected for hexavalent chromium using standard analysis techniques for metals in solids.

16. Cresols

See phenols.

17. Dioxins and furans

Here are the relevant monitoring techniques and standards.

17.1 Monitoring technique

The monitoring technique is isokinetic sampling of gas through a filter and resin trap, with subsequent extraction and analysis.

This technique can also be used to measure brominated dioxins and furans. The sampling and analysis may be combined with the sampling and analysis of chlorinated dioxin and furan samples.

Monitoring standard

The monitoring standard is EN 1948: parts 1, 2 and 3 and Environment Agency MID for EN 1948. The 3 parts cover sampling, extraction and quantification.

18. Ethylene dichloride

See VOCs (speciated).

19. Formaldehyde

Here are the relevant monitoring techniques and standards.

19.1 Monitoring technique 1

Monitoring technique 1 is isokinetic or non-isokinetic sampling and impingement. Analysis is by a choice of techniques based on either spectrophotometry or high performance liquid chromatography.

Monitoring standard

The monitoring standard is CEN TS 17638.

You must protect samples from direct sunlight and keep them at 5°C or less. You must analyse samples within 10 days.

You may also use USEPA M316 to measure formaldehyde until 31 March 2023. After this date MCERTS accreditation will no longer be available for this standard.

19.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a FTIR analyser.

Monitoring standard

The monitoring standard is CEN TS 17337

You may carry out non-isokinetic sampling if the stack gas does not contain droplets. If droplets are expected or occur you must carry out isokinetic sampling.

20. Flow

See gas velocity.

21. Gas velocity

Here are the relevant monitoring techniques and standards.

21.1 Monitoring technique

Several different techniques are specified for different applications.

• velocity measurement at point – differential pressure devices and vane anemometer
• determination of swirl – differential pressure devices able to determine flow direction (S-type, 2D or 3D Pitot tube)
• periodic measurement of average velocity in a duct – grid of point velocity measurements, tracer dilution technique, tracer transit time technique and calculation approach based on energy consumption
• calibration of continuous emissions monitoring systems (CEMS) for average velocity or volume - grid of point velocity measurements, tracer dilution technique, tracer transit time technique

Monitoring standard

The monitoring standard is EN 16911-1 and MID for EN 16911-1.

The MID for EN 16911-1 provides information on the application of EN 16911-1 to flow measurements used for isokinetic sampling, and for calculating mass emissions from periodic monitoring.

CEN/TR 17078 – Guidance on the application of EN 16911-1 is a technical report that provides guidance on applying the standard to a range of applications with different uncertainty requirements (that is calibration of CEMS and emissions trading).

22. Halogens and halides

Excludes techniques for monitoring hydrogen chloride and hydrogen fluoride.

Here are the relevant monitoring techniques and standards.

22.1 Monitoring technique 1

Monitoring technique 1 is non-isokinetic or isokinetic sampling and impingement. Analysis is by ion chromatography.

Monitoring standard

The monitoring standard is US EPA method 26 (non-isokinetic) and 26A (isokinetic).

Method 26 is for gas phase halides only; method 26A is for both aerosol and gas phase halides. It is also suitable for halogens with sulfuric acid scrubber to remove halides.

May be used for hydrogen bromide, chlorine and bromide.

You can measure chlorine dioxide by absorption in a weak basic potassium iodide solution (Occupational Safety and Health Administration – OSHA, Sampling and analytical methods – chlorine and chlorine dioxide in workplace atmospheres, 2011).

22.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a FTIR analyser.

It measures gas phase halides. It does not measure halogens.

Monitoring standard

The monitoring standard is CEN TS 17337.

22.3 Monitoring technique 3

Monitoring technique 3 is mass spectrophotometry.

This technique:

• can measure gas phase chlorine, bromine
• measures gas phase halides

Monitoring standard

There are no published monitoring standards.

23. Homogeneity test

Here are the relevant monitoring techniques and standards.

23.1 Monitoring technique

The monitoring technique is measuring gas concentrations using a grid measurement approach.

It determines whether the concentration of a stack gas pollutant is sufficiently homogenous at the sample plane location to allow you to sample it from a single point. It is also used to determine the location of CEMS.

Monitoring standard

The monitoring standard is EN 15259 (section 8.3) and MID for EN 15259.

24. Hydrogen chloride

Here are the relevant monitoring techniques and standards.

24.1 Monitoring technique 1

Monitoring technique 1 is isokinetic or non-isokinetic sampling and impingement. Analysis is by titration, spectrometry or ion chromatography.

It measures gas phase hydrogen chloride.

Monitoring standard

The monitoring standard is EN 1911.

24.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and an infrared analyser.

It measures gas phase hydrogen chloride.

Monitoring standard

The monitoring standard is EN 16429.

24.3 Monitoring technique 3

Monitoring technique 3 is extractive sampling and a FTIR analyser.

Monitoring standard

The monitoring standard is CEN TS 17337.

It measures gas phase hydrogen chloride.

EN 1911 and EN 16429 are standard reference methods. You may use CEN TS 17337 as an alternative methods, provided you meet the requirements specified in the MCERTS performance standard for stack emissions monitoring organisations.

25. Hydrogen cyanide

Here are the relevant monitoring techniques and standards.

25.1 Monitoring technique 1

Monitoring technique 1 is isokinetic sampling and impingement. Analysis is by ion chromatography.

Sampling is conducted isokinetically because of the solubility of hydrogen cyanide in water droplets, such as after wet scrubber systems. If you can prove that droplets are not present in the stack then you may carry out non-isokinetic sampling.

You can get an estimate of particulate cyanide by recovering and analysing the particulates on the filter. To do this you will need instructions for sample digestion and analysis.

Monitoring standard

The monitoring standard is US EPA OTM29.

It measures total gaseous cyanide.

High concentrations of acidic gases, including carbon dioxide, may lower the pH of the sodium hydroxide impinger solution. You must maintain the pH of the impingers at 12 throughout the sampling. You must also check this at the end of the test.

You may use lead acetate solution to remove sulfide interferences.

You may remove oxidizing agents (which may decompose cyanides in the impinger solutions) during sample recovery by adding ascorbic acid.

It specifies a 6.0N sodium hydroxide reagent solution. It gives a warning about safety issues using a solution of this strength. It also states that it may become difficult to analyse because of its viscosity. Because of this, you can use a weaker sodium hydroxide solution, provided you check the pH of the impingers at the end of the test to make sure the required pH has been maintained. An impinger efficiency test (less than 5% hydrogen cyanide in the last impinger) is a useful quality assurance check.

It specifies several requirements that are needed for US EPA methods but not for EN or ISO methods. The following changes to the method are acceptable, you:

• do not need to carry out a field blank spike
• do not need to measure carbon dioxide concentration of the stack gas for non-combustion processes
• may use a titanium probe and filter holder instead of glass

25.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a FTIR analyser.

Monitoring standard

The monitoring standard is CEN TS 17337.

This measures gas phase hydrogen cyanide.

26. Hydrogen fluoride

Here are the relevant monitoring techniques and standards.

26.1 Monitoring technique 1

Monitoring technique 1 is isokinetic or non-isokinetic sampling and impingement. Analysis is by ionometry, spectrophotometry and ion exchange chromatography.

You will need to carry out isokinetic sampling if droplets are present or when measuring particulate bound fluorides.

Monitoring standard

The monitoring standard is CEN TS 17340.

CEN TS 17340 measures fluorinated compounds and expresses them as hydrogen fluoride. It measures gas phase and particulate bound fluorides, or gas phase fluorides only.

27. Hydrogen sulfide

Here are the relevant monitoring techniques and standards.

27.1 Monitoring technique 1

Monitoring technique 1 is non-isokinetic sampling and impingement in cadmium sulfate. It is analysed iodometrically.

Monitoring standard

The monitoring standard is US EPA method 11.

It specifies using hazardous materials and potentially hazardous operations. Zinc acetate may be used in place of cadmium sulfate.

The range is from 8 mg/m³ to 740 mg/m³.

An impinger containing hydrogen peroxide is used to remove sulfur dioxide. You may omit this impinger from the sample train if no sulfur dioxide is present in the stack gas.

27.2 Monitoring technique 2

Monitoring technique 2 is non-isokinetic sampling and collection on charcoal tubes. It is analysed by ion chromatography.

Monitoring standard

The monitoring standards are:

• CEN TS 13649 for sampling
• NIOSH 6013 for analysis

Sulfur dioxide is a positive interferent, so it is not suitable for some combustion processes.

It is useful for odour work because of the lower limit of detection (LOD) than the US EPA method 11. NIOSH 6013 states the LOD for a 20 litre sample is 0.9 mg/m³.

It can also be used for measuring the hydrogen sulfide content of natural gas.

27.3 Monitoring technique 3

Monitoring technique 3 is a portable gas chromatograph with a suitable detector.

Monitoring standard

The monitoring standard is US EPA method 15.

Its LOD is 0.5 ppm.

28. Isocyanates

Here are the relevant monitoring techniques and standards.

28.1 Monitoring technique 1

Monitoring technique 1 is isokinetic sampling onto a filter coated with 1-(2-pyridyl) piperazine. Analysis is by high performance liquid chromatography.

Monitoring standard

The monitoring standards are US EPA conditional test method (CTM) 36 for sampling and CTM 36 A for analysis.

The standard refers to specific isocyanates but you may also use it for other isocyanates.

You may use a titanium probe and filter holder instead of glass. Using titanium for sample trains is not specified in US EPA methods. However, it is acceptable in CEN and ISO monitoring standards. You may use an out of stack filter.

29. Mercury

29.1 Monitoring technique

The monitoring technique is isokinetic sampling of gas through a filter and absorber solutions. The filter and absorber solutions are analysed in a laboratory.

Monitoring standard

The monitoring standard is EN 13211.

It is for the determination of mercury and its compounds in all phases.

30. Mercaptans (thiols)

Here are the relevant monitoring techniques and standards.

30.1 Monitoring technique 1

Monitoring technique 1 is extractive sampling onto a desorption tube, with subsequent desorption and analysis. This is done with a molecular sieve or a dual bed sorbent thermal desorption tube. These must have an inert coating designed for sulfur compounds, including mercaptans.

Monitoring standard

The monitoring standard is CEN TS 13649 for sampling. There are no published standards for analysis.

30.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling onto a mercuric acetate treated filter. Analysis is by gas chromatography with a suitable detector.

Monitoring standard

There are no published monitoring standards. NIOSH 2542 is for analysis.

31. Metals (total)

Here are the relevant monitoring techniques and standards.

31.1 Monitoring technique 1

Monitoring technique 1 is isokinetic sampling of gas through a filter and absorber solutions. The filter and absorber solutions are analysed in a laboratory.

Monitoring standard

The monitoring standard is EN 14385 and MID for EN 14385.

It is for the determination of total emissions of:

• Antimony
• Arsenic
• Cadmium
• Chromium
• Cobalt
• Copper
• Lead
• Manganese
• Nickel
• Thallium
• Vanadium

The MID provides an option for other metals, such as tin and zinc.

32. Methane

Here are the relevant monitoring techniques and standards.

32.1 Monitoring technique 1

Monitoring technique 1 is extraction into a gas sampling bag or canister. Analysis is by gas chromatography with a flame ionisation detector (FID).

Monitoring standard

The monitoring standard is EN 25139.

32.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a FID analyser. A catalytic converter is used to oxidise all organic compounds in the extracted gas, with the exception of methane.

Monitoring standard

The monitoring standard is EN 25140.

32.3 Monitoring technique 3

Monitoring technique 3 is extractive sampling and a FTIR analyser.

Monitoring standard

The monitoring standard is CEN TS 17337.

EN 25410 is a reference method. You may use CEN TS 17337 as an alternative method, provided you meet the requirements specified in the MCERTS performance standard for stack emissions monitoring organisations.

33. Methanol

Here are the relevant monitoring techniques and standards.

33.1 Monitoring technique 1

Monitoring technique 1 is extractive sampling onto a sorbent tube with subsequent desorption and analysis.

Monitoring standard

The monitoring standards are:

• CEN TS 13649 for sampling
• NIOSH 2000 or OSHA 91 for analysis

OSHA 91 has been withdrawn by OSHA but is available online and you may still use it.

NIOSH 2000 specifies silica gel tubes. OSHA 91 specifies anasorb carbon tubes.

33.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a FTIR analyser.

Monitoring standard

The monitoring standard is CEN TS 17337.

34. Moisture

See water vapour (moisture).

35. Nitric acid vapour

Here are the relevant monitoring techniques and standards.

35.1 Monitoring technique 1

Monitoring technique 1 is non-isokinetic sampling into impingers containing alkaline potassium permanganate. Analysis is by ion chromatography.

Monitoring standard

The monitoring standard is US EPA M7d.

You should use this for processes which may emit nitric acid vapour emissions, such as the surface treatment of metals.

35.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a FTIR analyser.

Monitoring standard

The monitoring standard is CEN TS 17337.

36. Nitrogen monoxide and nitrogen dioxide

Here are the relevant monitoring techniques and standards.

36.1 Monitoring technique 1

Monitoring technique 1 is extractive sampling and a chemiluminescence analyser.

For processes that have a significant amount of nitrogen dioxide, you may need to use a different analytical technique to chemiluminescence. This is due to the:

• greater relative importance of the nitrogen dioxide
• potential difficulty in maintaining the 95% nitrogen dioxide to nitrogen monoxide converter efficiency

Examples include the production of dye-stuffs in the chemical industry or the brightening of aluminium components in acid baths.

Monitoring standard

The monitoring standard is EN 14792.

Determining the nitrogen dioxide converter efficiency should be carried out by an organisation that has MCERTS accreditation for EN 14792.

If an analyser is only used for monitoring processes that have less than 10% nitrogen dioxide to nitrogen oxides ratio, the converter efficiency must be demonstrated at least every year.

If an analyser is used on processes with over 10% nitrogen dioxide to oxides of nitrogen ratio, the monitoring organisation must determine how often to carry out the converter efficiency check. The frequency is based on the:

• length of time the analyser is used on processes with over 10% nitrogen dioxide to oxides of nitrogen ratio
• concentration of nitrogen dioxide encountered
• expected life span of the converter material

If the converter does not meet the conversion efficiency, then monitoring work on processes with over 10% nitrogen dioxide, carried out since it last met the converter efficiency, will not comply with EN 14792.

If an analyser is used on processes with over 10% nitrogen dioxide to oxides of nitrogen ratio, the monitoring organisation must determine the converter efficiency before the material in the converter is replaced.

If the converter does not meet the 95% converter efficiency, then monitoring work on processes with over 10% nitrogen dioxide, carried out since it last met the converter efficiency, will not comply with EN 14792.

Monitoring organisations can check the converter efficiency using a cylinder of nitrogen dioxide, as soon as practicable after they have proved that the converter efficiency is acceptable. They can then use this cylinder to provide checks of the converter between carrying out gas phase titration checks.

36.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a FTIR analyser.

Monitoring standard

The monitoring standard is CEN TS 17337.

They measure nitrogen monoxide and nitrogen dioxide.

EN 14792 is the standard reference method. You may use an alternative method provided you meet the requirements specified in the MCERTS performance standard for stack emissions monitoring organisations.

37. Nitrous oxide (dinitrogen monoxide)

Here are the relevant monitoring techniques and standards.

37.1 Monitoring technique 1

Monitoring technique 1 is extractive sampling and a NDIR analyser.

Monitoring standard

The monitoring standard is EN ISO 21258.

Interference is from carbon dioxide. You may need to measure carbon dioxide, so that it can be compensated for.

You must remove water vapour.

37.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a FTIR analyser.

Monitoring standard

The monitoring standard is CEN TS 17337.

EN ISO 21258 is a reference method. You may use an alternative method provided you meet the requirements specified in the MCERTS performance standard for stack emissions monitoring organisations.

38. Odour

Here are the relevant monitoring techniques and standards.

38.1 Monitoring technique

The monitoring technique is extractive sampling into inert containers. Assessment is by olfactometry using an odour panel. The unit of measurement is the European odour unit per cubic metre (ouE/m³). You may use this method to measure the emission rate of odorous emissions from stacks.

Monitoring standard

The monitoring standard is EN 13725 and the MID for EN 13725.

39. Oil mist

Here are the relevant monitoring techniques and standards.

39.1 Monitoring technique

The monitoring technique is isokinetic sampling, extraction into cyclohexane, then gravimetric analysis.

This technique measures fume and condensed vapours, not volatiles.

Sticky particulates can foul sampling equipment leading to low recoveries unless you take precautions (for example, using an in-stack filter).

You may set up the sample train with an out of stack filter at ambient temperature. You can use this indicative method to identify if oil mist is contributing to a visible plume.

Monitoring standard

The monitoring standard is EN 13284-1 for sampling methods for the determination of hazardous substances (MDHS) 84 for analysis.

MDHS 84 only includes the analysis of oil mist collected on a filter. To comply with EN 13284-1, you must analyse oil mist collected by a cyclohexane or acetone rinse on the equipment upstream of the filter.

40. Oxygen

Here are the relevant monitoring techniques and standards.

40.1 Monitoring technique 1

Monitoring technique 1 is extractive sampling and a paramagnetic analyser.

Monitoring standard

The monitoring standard is EN 14789.

40.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a zirconium cell.

EN 14789 is the standard reference method. You may use an alternative technique provided you meet the requirements specified in the MCERTS performance standard for stack emissions monitoring organisations.

40.3 Monitoring technique 3

Monitoring technique 3 is electrochemical cell.

Monitoring standard

EN 14789 is the standard reference method. You may use an alternative technique provided you meet the requirements specified in the MCERTS performance standard for stack emissions monitoring organisations.

41. Polycyclic aromatic hydrocarbons (PAHs)

Here are the relevant monitoring techniques and standards.

41.1 Monitoring technique

Monitoring technique 1 is isokinetic sampling of gas through a filter and resin trap, with subsequent extraction and analysis.

The regulatory authorities specify the set of PAH compounds that you should measure. This set may vary depending on the process or purpose of the measurement. You should make sure that the analytical laboratory analyses the PAH compounds specified.

Monitoring standard

The monitoring standards are ISO 11338-1 and 11338-2.

You may transport PAH samples below 25°C before storing in cold conditions. This requirement is taken from VDI 3874:2006, which states that samples must be transported at ambient temperature and protected from light.

42. Particulate matter

Here are the relevant monitoring techniques and standards.

42.1 Monitoring technique

The monitoring technique is isokinetic sampling followed by weighing.

Monitoring standard

The monitoring standard is EN 13284-1 and the MID for EN 13284-1. It is a supporting standard for manual sampling methods. You can apply the field blank procedure and leak check requirements specified in this standard to other manual monitoring methods.

43. Particulate matter (condensable)

Here are the relevant monitoring techniques and standards.

43.1 Monitoring technique

The technique uses a cyclone and isokinetic sampling to measure PM₁₀ and PM_2.5. It includes a dilution sampling technique to measure condensable secondary particulate matter that is similar in character to ambient particulate matter.

Monitoring standard

The monitoring standard is ISO 25597.

Under MCERTS accreditation and the hierarchy of standards, PM₁₀ and PM_2.5 is measured using EN ISO 23210.

44. Particulate matter size fractionation

Here are the relevant monitoring techniques and standards.

44.1 Monitoring technique

The monitoring technique is impaction using a 2 stage cascade impactor to measure PM₁₀ and PM_2.5 concentrations simultaneously.

Monitoring standard

The monitoring standard is EN ISO 23210.

This is the standard reference method.

It is applicable for particulate concentrations between 1 and 50 mg/m³. For stack gas emissions with particulate concentrations above 50 mg/m³ the following are available:

• ISO 25597: test method for determining PM_2.5 and PM₁₀ mass in stack gases using cyclone samplers and sample dilution
• ISO 13271: determination of PM₁₀ and PM_2.5 mass concentration in flue gas - measurement at higher concentrations by use of virtual impactors

It cannot be used:

• to measure stack gases that are saturated with water vapour
• for stack gases where the majority of particulates are greater than PM₁₀
• to measure total mass concentration of particulates

You should position a cascade impactor in the stack, so that it points in the same direction as the flow. If there is restricted access into the stack, you must install the impactor into the stack at 90° to the flow direction, and use a goose neck nozzle to make sure the nozzle points into the direction of flow.

You should locate a fixed sample point at a representative point within the stack. It is difficult to find a representative point based on the distribution of particulates, so the standard suggests you can use an alternative, such as temperature or oxygen. Although not referred to in the standard, velocity would also be a suitable alternative.

45. Polychlorinated biphenyls (PCBs) dioxin like

Here are the relevant monitoring techniques and standards.

45.1 Monitoring technique

The monitoring technique is isokinetic sampling of gas through a filter and resin trap, with subsequent extraction and analysis.

Monitoring standard

The monitoring standard is EN 1948-4.

46. Phenols and cresols

Here are the relevant monitoring techniques and standards.

46.1 Monitoring technique

The monitoring technique is extractive sampling onto XAD-7 sorbent resin, followed by methanol desorption and analysis.

Monitoring standard

The monitoring standards are:

• CEN TS 13649 for sampling
• OSHA 32 or NIOSH 2546 for analysis.

OSHA 32 has a LOD of 0.05 mg/m³.

NIOSH 2546 has a LOD of 1 mg/m³.

Phenols and cresols entrain in moisture droplets, so you should sample them isokinetically when stack gas moisture levels are above saturation for a given temperature.

47. Phosphorous and its inorganic compounds

Here are the relevant techniques and standards.

47.1 Monitoring technique 1

Monitoring technique 1 is non-isokinetic extraction and impingement. Analysis is by visible spectrophotometry.

This technique is for gas phase only.

Monitoring standard

The monitoring standards are the procedural requirements of EN 14791 for sampling and NIOSH 6402 for analysis.

It is specific to phosphorous trichloride.

47.2 Monitoring technique 2

Monitoring technique 2 is non-isokinetic extraction and adsorption onto mercuric cyanide treated silica gel tubes. Analysis is by colorimetry.

This technique is for gas phase only.

Monitoring standard

The monitoring standards are:

• the procedural requirements of CEN TS 13649
• NIOSH 6002 for analysis or OSHA ID180

It is specific to phosphine (also known as phosphane).

47.3 Monitoring technique 3

Monitoring technique 3 is isokinetic sampling of gas through a filter and absorber solutions. The filter and absorber solutions are analysed in a laboratory.

This technique is for total phosphorous in all phases.

Monitoring standard

The monitoring standard is EN 14385 (see metals).

Speciation of phosphorous compounds is not possible.

48. Selenium

Here are the relevant techniques and standards.

48.1 Monitoring technique

The monitoring technique is isokinetic sampling of gas through a filter and absorber solutions. The filter and absorber solutions are analysed in a laboratory.

It measures selenium in the particulate and gas phase.

Monitoring standard

The monitoring standard is ISO 17211.

49. Siloxanes

When gas containing siloxanes passes through a combustion process (for example a gas engine or a flare stack) the siloxanes are primarily converted to silicon dioxide.

Silicon dioxide emissions are measured using particulate sampling techniques (EN 13284-1). Here are the relevant monitoring techniques and standards for siloxanes.

49.1 Monitoring technique 1

The monitoring sampling techniques are:

• impingers with methanol
• charcoal sorbent tubes
• canisters
• evacuated bag

Extraction, if required, and analysis technique depends on the sampling approach used.

Monitoring standard

The monitoring standards are CEN TS 13649 or EN 14791 for sampling. Their main use is to measure untreated gas, such as raw landfill gas before it enters a gas engine.

49.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a FTIR analyser.

Monitoring standard

The monitoring standard is CEN TS 17337.

50. Speciated VOCs

See VOCs (speciated).

51. Sulfur dioxide

Here are the relevant techniques and standards.

51.1 Monitoring technique 1

Monitoring technique 1 is non isokinetic or isokinetic extraction and impingement into hydrogen peroxide solution. Analysis is by ion chromatography or Thorin method.

Monitoring standard

The monitoring standard is EN 14791.

51.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and measurement with an analyser.

Monitoring standard

The monitoring standard is CEN TS 17021.

It is based on the generic analyser technique. It specifies performance criteria, rather than a specific analyser technique.

You can use a performance criterion of 5% of the measured value for the losses and leakage in both the:

• sample gas line
• sample gas conditioning system performance characteristic

This performance criterion has an impact on measurement uncertainty. It is your responsibility to make sure that your measurement uncertainty meets the relevant requirements.

EN 14791 is the standard reference method. CEN TS 17021 may be used as an alternative method, provided you meet the requirements specified in the MCERTS performance standard for stack emissions monitoring organisations.

Some NDIR analysers may suffer from interference from methane. This may be an issue when measuring emissions from landfill gas engines and biowaste plants. You should make appropriate provisions to quantify the interference.

Instrument type testing specifies that the collective interference value must not be more than 4% of the certification range at either the zero or span point. You should refer to the MCERTS certificate to find the interference effects of methane.

If the methane interference effect is more than 4%, you must use another technique.

51.3 Monitoring technique 3

Monitoring technique 3 is extractive sampling and a FTIR analyser.

Monitoring standard

The monitoring standard is CEN TS 17337.

EN 14791 is the standard reference method. CEN TS 17337 may be used as an alternative method, provided you meet the requirements specified in the MCERTS performance standard for stack emissions monitoring organisations.

52. Sulfuric acid including sulfuric acid mist and sulfur trioxide

Here are the relevant techniques and standards.

52.1 Monitoring technique

The monitoring technique is isokinetic extraction and impingement with propan-2-ol. Analysis is by titration or ion chromatography.

The technique measures sulfuric acid, including sulfuric acid mist and sulfur trioxide.

These cannot be measured separately, so you get a combined result.

Monitoring standard

The monitoring standard is US EPA method 8.

53. Stibine (also known as stibane)

Here are the relevant monitoring techniques and standards.

53.1 Monitoring technique

The monitoring technique is extractive sampling onto sorbent tube made of mercuric chloride coated silica gel. Analysis is by solvent extraction followed by visible spectrophotometry.

Monitoring standard

The monitoring standards are CEN TS 13649 for sampling and NIOSH 6008 for analysis.

54. Tar and bitumen fume

Here are the relevant monitoring techniques and standards.

54.1 Monitoring technique

The monitoring technique is isokinetic sampling, followed by extraction into cyclohexane, then gravimetric analysis.

This technique measures total particulate first. Tar or bitumen is determined as the weight loss after the filters are treated with cyclohexane.

This technique measures fume and condensed vapours, not volatiles. Although you can use a condensation or resin trap if you need to measure volatiles.

Sticky particulates can foul sampling equipment, leading to low recoveries unless you take precautions – for example, using an in-stack filter.

Monitoring standard

The monitoring standard is EN 13284-1 with analysis based on MDHS 84.

55. Temperature

See gas velocity.

56. Tetrachloromethane

See VOCs (speciated).

57. Thiols

See mercaptans.

58. Tin

See metals.

59. Total cyanide

See hydrogen cyanide.

60. Total organic compounds

See VOCs (total).

61. Total reduced sulfur compounds (TRS)

Here are the relevant monitoring techniques and standards.

61.1 Monitoring technique 1

Monitoring technique 1 is non-isokinetic sampling, followed by combustion of sulfur in the sample to sulfur dioxide. Analysis is by titration.

Monitoring standard

The monitoring standards are US EPA methods:

• 15A (combustion air added)
• 16A (no combustion air added)

No speciation is possible.

61.2 Monitoring technique 2

Monitoring technique 2 is sampling through a tube furnace and combustion of sulfur in the sample to sulfur dioxide. Analysis is by flame-photometric detection.

Monitoring standard

The monitoring standard is US EPA method 16B.

62. Total sulfur

See sulfur trioxide.

63. Total VOCs

See VOCs (total).

64. Trace metals

See metals.

65. Vinyl chloride monomer

See VOCs (speciated).

66. VOCs (speciated)

Here are the relevant techniques and standards.

66.1 Monitoring technique 1

Monitoring technique 1 is extractive sampling onto sorbent tubes, followed by solvent extraction and analysis.

Monitoring standard

The monitoring standard is CEN TS 13649.

You can apply it to a wide range of aliphatic and aromatic VOCs. You can sample directly or use dilution to avoid condensation.

You may use it to quantitatively measure total VOCs, provided you have identified the VOCs before sampling. If the stack gas contains an unknown mixture of VOCs you cannot use this method to give a total VOC measurement.

When you are using a different absorption medium, it is acceptable to use thermal desorption. You must have evidence to show that the proposed desorption and analytical techniques are valid.

Sample tubes must be stored and transported below 25°C in an airtight VOC free container, without exposure to direct sunlight. You may store samples under these conditions for a prolonged time period. If you are storing samples for more than 7 days before analysis, you do not need to store them below 4°C.

For some VOCs, you may need to take account of the analytical requirements of occupational hygiene standard methods published by NIOSH and OSHA, for example:

• sorbent
• extraction method
• column
• detector

66.2 Monitoring technique 2

Monitoring technique 2 is extractive sampling and a portable gas chromatograph with an appropriate detector.

Monitoring standard

The monitoring standard is US EPA method 18.

66.3 Monitoring technique 3

Monitoring technique 3 is extractive sampling and a portable FTIR analyser.

Monitoring standard

The monitoring standard is CEN TS 17337.

67. VOCs (total)

VOCs (total) are also referred to as total organic carbon (TOC).

Here are the relevant monitoring techniques and standards.

67.1 Monitoring technique 1

Monitoring technique 1 is extractive sampling and FID analyser.

Monitoring standard

The monitoring standard is EN 12619.

Interference from oxygen is reduced by using a mixed hydrogen and helium fuel.

You need to check interference from oxygen at 10% and 20%. This applies to combustion processes, especially when calibrating a CEMS for EN 14181 purposes.

If the FID does not meet the performance criteria at these concentrations, gases with an oxygen concentration similar to stack gas should be used for the zero and span checks at combustion processes, with emissions typically around 10% oxygen (for example, waste incineration plants).

Monitoring technique 2

Monitoring technique 2 is extractive sampling and a NDIR analyser equipped with a catalytic converter for the oxidation of VOCs to carbon dioxide.

Unlike FID techniques this approach does not have a flame or hydrogen fuel, so you can use it in applications where you must use intrinsically safe equipment.

The VOCs have the same response factors because they are oxidised to carbon dioxide. The technique does not have cross interference from oxygen.

Monitoring standard

The monitoring standard is EN ISO 13199.

It cannot be used to measure emissions from combustion processes. It may be used on painting and printing processes.

68. Water vapour (moisture)

Here are the relevant techniques and standards.

68.1 Monitoring technique 1

Monitoring technique 1 is extractive sampling into impingers and gravimetric analysis.

Monitoring standard

The monitoring standard is EN 14790.

It is incorporated into several other periodic manual methods. This allows you to measure moisture as part of another sampling method.

The technique is not applicable for saturated conditions.

68.2 Monitoring technique 2

Monitoring technique 2 is a FTIR analyser.

Monitoring standard

The monitoring standard is CEN TS 17337.

EN 14790 is the standard reference method. You may use CEN TS 17337 provided you meet the requirements specified in the MCERTS performance standard for stack emissions monitoring organisations.

69. Zinc

See metals.