Environmental guidance for your business in Northern Ireland & Scotland

Prevent dark smoke

Prevent dark smoke


You must not cause or allow a chimney or bonfire on your site to emit dark smoke. There are some exemptions from this requirement, but only if your installation won't cause emissions that could damage health or cause a nuisance.

What is dark smoke?

The darker the smoke, the more polluting it tends to be. Smoke darker than a specified shade of grey is officially classified as 'dark smoke'.

A Ringelmann chart is used to define dark smoke. The chart has five shades of grey with 0 being clear and 5 being black. Smoke is considered 'dark' if it has a shade of 2 or darker.

The Ringelmann chart: British Standard BS 2742C


What you must do

You must prevent the emission of dark smoke from:

  • chimneys serving furnaces, fixed boilers or industrial plants, whether they are attached to buildings or not
  • any industrial or trade premises.

Industrial or trade premises include:

  • the site where you are working, such as a building or demolition site
  • any site that you own or lease
  • land used for commercial agriculture or horticulture.

Be aware that you cannot use a defence of lack of visual evidence, if you burn materials at night for example. Your local council does not need to see the emissions of dark smoke to take action against you. Evidence of burnt materials that could cause dark smoke, such as steel reinforcement from tyres, or plastic residues is sufficient.

Permits and exemptions for burning waste

If you burn waste in an appliance, such as a furnace or boiler, you will usually require a pollution prevention and control permit, waste management licence or a waste exemption.

You must not burn waste in the open, such as on a bonfire, unless you have a waste management licence or a registered waste exemption that covers this activity.

If you have a permit, licence or waste exemption you must comply with all of its conditions.

See our guideline: Waste incineration


Further information

 Environmental Protection UK: Air pollution sources

 UK Air - DEFRA air information resource: Air quality forecasts and latest measured air quality

 Northern Ireland Air: Air quality forecasts and latest measured air quality

 Air Quality in Scotland: Air pollution levels and forecasts

 Find your local council


In this guideline

Causes and effects of air pollution

Business benefits of improving air quality

What you must do to prevent air pollution

Prevent dark smoke

Boilers and furnaces: environmental authorisations

Boilers and furnaces - chimney height requirements

Burning waste controls

Smoke control areas

Protecting neighbours from air pollution

Measuring and monitoring to reduce air pollution

Air pollution environmental legislation

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