The most harmful environmental impacts from furnaces are from emissions of particulates (dust) and fumes. An electric or gas furnace will generate less particulate emissions than other types of furnace.

What you must do


Check with your environmental regulator or local council to see if you need a permit for your furnace. You may need a pollution prevention and control (PPC) permit.

If you have a permit, you must comply with its conditions. Your permit may contain conditions relating to your levels of noise, vibration, odour and dust and smoke emissions.

Contact your environmental regulator

Pollution prevention and control permits

Odour and nuisance

You must make sure that your business does not cause a nuisance to your neighbours or the local community. Nuisances include smoke, dust, odour, noise and vibration. Anyone affected by a nuisance can take legal action against you or your business, or complain to your local council.

If your business causes a nuisance, or could cause or repeat a nuisance, you can be issued with an abatement notice. Your local council's environmental health department or the courts can issue abatement notices. You can be fined if you do not comply with an abatement notice.

An abatement notice can:

  • stop or impose restrictions on your operations
  • require you to carry out works or take other steps to restrict or remove the nuisance.

For further information see our guidance on Noise, odour and other nuisances.

Installing a furnace

Your local council must approve your plans before you use any new furnace, or make changes to an existing furnace.

If you have local council consent for your installation, you still cannot emit dark smoke. All new furnace installations must be able to run continuously without emitting smoke. In Scotland furnaces must be fitted with grit and dust arrestment plant. You can apply for an exemption from this requirement, but only if your installation will not cause emissions that could damage health or cause a nuisance.

Your local council regulates chimney height if your furnace fuel consumption exceeds 45.4kg of solid fuel or 366.4kW of liquid or gas fuel per hour. Your chimney must be high enough to prevent smoke, grit, dust, gas and fume emissions from damaging health or causing a nuisance.

Preventing air pollution

Contact your local council

Sulphur content of fuels

You must not use gas oil with a sulphur content exceeding 0.1% by mass.

You must not use heavy fuel oil with a sulphur content exceeding 1% by mass. This is particularly relevant if you have stocks of stand-by fuel that remain unchanged for considerable periods of time. If you operate pre-1987 combustion plant you can apply for a 'sulphur content of liquid fuels' permit from SEPA in Scotland or from the Industrial and Radiochemical Inspectorate in Northern Ireland.

Contact your local council

Contact your environmental regulator


If you prepare material by incineration, or you use waste oil or recovered fuel oil to fire your furnace, check if the Waste Incineration Directive will affect your operations.

Waste incineration

Radioactive sources

Some level-detection and smoke detection devices on furnaces use radioactive sources. If your furnace uses a radioactive source, you must have a certificate of registration or authorisation from your environmental regulator.

Radioactive materials: Registration, authorisation and exemptions

Good practice

Using your furnaces efficiently

  • Consider whether you could use more environmentally friendly furnace fuel.
  • Make sure you are using the most efficient furnace for your process. For example, an electric induction furnace emits one tenth of the particulate emissions of a cupola furnace.
  • Follow the start-up procedures recommended by the furnace manufacturer. Allow sufficient time when lighting up your furnace from cold. This will enable your furnace to run more efficiently and avoid unnecessary emissions and fuel use.
  • Service your extraction systems regularly and repair defects or damage promptly. This will ensure you keep emissions to a minimum and you operate your furnace efficiently.
  • Put materials into batches and use programmed heating controls in order to improve energy efficiency.

Furnace charge material

  • Pelletise fine feed materials before you introduce them to smelting or melting furnaces. This will reduce dust emissions.
  • Only melt material which is compatible with your furnace. This will help your furnace to operate efficiently.
  • Maximise the metallic content of the charge material. This will minimise the amount of solid waste material produced and reduce energy use.
  • Only melt clean scrap in your furnace, unless you have registered an exemption with your environmental regulator that allows you to use contaminated scrap.

Waste exemptions for metals production and processing businesses

Dust and fumes

  • Use hooding and bag filters to capture fumes and dust from furnaces. This is particularly important where you charge the furnace, and where you remove molten metal, dross and slag.
  • Minimise transfers of molten metal to reduce emissions. Cover transfer points wherever possible to keep air away from molten metal.
  • Maintain strict temperature control when alloying. This prevents metal fuming.
  • Use automated burner controls to reduce polluting emissions.
  • Remove as much lubricating emulsion as possible before annealing to reduce polluting emissions to air.

Replacing furnaces

  • Replace oil-fired burners with gas or electric alternatives when a furnace reaches the end of its life. This will help you to reduce emissions.
  • Design new plant to reduce and control emissions.

Recovering materials and heat

  • You may be able to recover metals and salts from some slags. This will reduce the amount of waste you produce.
  • You may be able to use steel slag as a secondary aggregate, for example roadstone, if the metal content is not too high. However, steel slag is considered to be a waste so you must comply with appropriate waste regulations, for example you need to transport it using a waste carrier and with a waste transfer note. Contact trade associations such as the British Aggregates Association or the Mineral Products Association for further information on using slag.

British Aggregates Association

Mineral Products Association

  • Blast furnace slag is considered separately to steel slag, and is regarded as a by-product.
  • Use recuperative or regenerative burners to recover heat from exhaust gases.
  • Reduce fuel use by recovering waste heat to use in other parts of your operation.


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