Guidance

Chemicals: pollution inventory reporting

Updated 29 November 2024

Applies to England

• Publication for Northern Ireland
• Publication for Scotland
• Publication for Wales

If you operate an A1 facility, you must submit data to the pollution inventory. The Environment Agency will have sent you a notice explaining this when your environmental permit was issued.

The ‘general guidance’ available in the pollution inventory reporting guidance gives information that applies to all business and industries. It explains what the pollution inventory is and how to report.

This guidance gives information specific to the chemicals sector.

If your operations include waste incineration or combustion, you may also find the guidance for those sectors useful.

Emissions to air

Relevant pollutants

The most common air emissions for the chemicals sector are:

• ammonia
• anthracene
• arsenic
• asbestos
• benzene
• 1,3-butadiene
• cadmium
• carbon dioxide
• carbon monoxide
• carbon tetrachloride
• chlorine and inorganic compounds, as hydrogen chloride (HCl)
• chlorofluorocarbons
• chloroform
• chromium
• copper
• dichloromethane (DCM) (methylene chloride)
• di-(2-ethyl hexyl) phthalate
• dioxins and furans
• ethylene dichloride (1,2-dichloroethane)
• ethylene oxide
• fluorine and inorganic compounds as HF
• hydrochlorofluorocarbons (HFCs)
• hydrofluorocarbons
• hydrogen cyanide
• lead
• mercury
• methane
• methyl chloroform (trichloroethane)
• naphthalene
• nickel
• nitrogen dioxide (nitrogen oxides – NO and NO₂ as NO₂)
• nitrous oxide
• non-methane volatile organic compounds (NMVOCs)
• particulate matter (total, PM2.5 and PM10)
• perfluorocarbons (PFCs)
• polychlorinated biphenyls
• sulfur hexafluoride
• sulfur oxides (SO₂ and SO₃ as SO₂)
• tetrachloroethane
• tetrachloroethylene
• trichlorobenzene
• trichloroethylene
• vinyl chloride
• zinc

Use this as a guide only. You must check for other pollutants emitted from your process.

Emission sources

Point source emissions

These emissions are exhausted via a stack or vent, into the atmosphere from a single point source. Abatement equipment, such as scrubbing units and fabric filters (bag house) can be incorporated into the exhaust system prior to discharge to atmosphere.

Fugitive emissions

Fugitive emissions are those that are not released from a point source. These are sometimes called diffuse emissions. Only fugitive emissions that leave the site need to be reported to the pollution inventory.

Contained spills do not need to be reported to the pollution inventory, but you should report vapour emissions that may have dispersed. Any spills may still need to be reported in other ways as part of your permit conditions.

In some chemical production activities, fugitive emissions may be more significant than point source emissions. Fugitive volatile organic compound (VOC) emissions are often a significant factor in emissions to air from large volume organic chemicals installations. Some examples of the potential sources of fugitive emissions to air are:

• loading and unloading of materials into transport containers
• storage areas (for example, bays, stockpiles, and so forth)
• transferring material between vessels
• conveyor systems
• pipework and ductwork systems (for example, pumps, valves, flanges, equipment vents)
• accidental loss of containment from failed plant and equipment
• poor building containment and extraction

Emission factors, feedstock analysis and process stream data

Check the ‘general guidance’ in the pollution inventory reporting guidance for information about how you can use emission factors.

In the chemical industry, the emission factor you need is sometimes based on feedstock analysis data. This is especially relevant for SO₂.

The use of feedstock analysis and process stream data to determine emissions is similar to the use of emission factors.

Check the ‘technical guidance and equations’ in the pollution inventory reporting: guidance notes for equations you might need.

The basic equation used in feedstock analysis emission calculations is equation 7. This is the method usually used for calculating SO₂ emissions where it is normally assumed that all the sulfur in the feedstock is converted to SO₂.

Where the pollutant concentration in the feedstock is consistent over the averaging period (that is, one year), you can use equation 8.

You can also use equation 7 for volatile elements such as fluorine and chlorine, and for trace metallic pollutants. Some of these species are retained in the plant, either in the ash or in abatement equipment. You should apply appropriate retention factors.

When using equation 7 or equation 8, you should be aware that the amounts of pollutants present in the feedstock or process stream can vary significantly.

Emissions to water

Emissions of substances to water can be either direct to controlled waters or indirect, following transfer to off-site effluent treatment plant.

Check the ‘general guidance’ in the pollution inventory reporting guidance for what constitutes an emission or a transfer.

We recognise that you may have trouble disaggregating EPR and non-EPR releases of substances to water where both pass through a common monitoring point as a combined effluent. Use the combined effluent value where it is not possible to estimate the individual contributions.

Relevant pollutants and emission sources

Water discharges from chemical processes arise from:

• air abatement equipment (for example, wet scrubbers)
• storm water
• cooling water
• boiler blow-down
• raw material handling areas
• accidental emissions of raw materials
• products or waste materials
• firefighting
• on-site effluent treatment

Some of the most common water emissions for the chemicals sector are:

• anthracene
• arsenic
• benzene
• benzo(g,h,i)perylene
• cadmium
• chlorides as total Cl
• chloroform (trichloromethane)
• chloropyrifos
• chromium
• copper
• cyanides as total CN
• dichloromethane (DCM) (methylene chloride)
• ethylene dichloride (1,2-dichloroethane)
• dioxins and furans
• diuron
• ethyl benzene
• ethylene oxide
• fluorides as total F
• halogenated organic compounds – as adsorbable organic halides (AOX)
• hexachlorobenzene
• hexachlorobutadiene
• lead
• mercury
• naphthalene
• nickel
• nitrogen (total)
• nonylphenols and ethoxylates
• octylphenols and ethoxylates
• organotin compounds
• pentachlorophenol
• phenols
• phosphorus (total)
• polychlorinated biphenyls
• tetrachloroethylene
• toluene
• total organic carbon (TOC)
• tributyltin
• trichlorobenzenes
• trichloroethylene
• trifluralin
• vinyl chloride
• xylene – all isomers
• zinc

Use this list as a guide only and check for other pollutants emitted from your process.

The resulting discharge of the above substances depends on your ‘in process’ preventative measures (good housekeeping, re-use). It also depends on the presence and technical standards of your wastewater treatment facilities.

Off-site waste transfers

Relevant wastes

You must classify wastes using the European Waste Catalogue 6-digit codes and the relevant Waste Framework Directive disposal or recovery codes. Check the ‘reporting codes list’ in the pollution inventory reporting guidance.

In general, the waste streams from chemical facilities can be classified into types as follows:

• by-products for which no internal use or external sale is available
• residues from separation processes such as distillation
• catalysts which have declined in performance and require replacement
• filter cake, activated carbon, ion exchange resins, molecular sieves and other treatment materials
• sludges from wastewater treatment
• emptied containers and packaging
• maintenance and construction materials

You can identify the key substances likely to be present through your knowledge of:

• the process
• materials of construction
• corrosion or erosion mechanisms
• materials related for maintenance

You should also identify substances created by abnormal operation.