Dark smoke

Dark smoke

The Clean Air Act 1993 makes it an offence to emit dark smoke from any trade or industrial premises or to emit dark smoke from the burning of trade or industrial waste. The emission of dark smoke is a strict offence and can be immediately prosecuted in the Magistrate's Court to a maximum of £20,000 per offence.

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. Using the Ringelmann Chart is the British Standard method of assessment (BS 2742C - 1957 and BS 2742:2009).

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

The local authority does not need to see the emissions of dark smoke to take action. Evidence of burnt materials that could cause dark smoke, such as steel reinforcement from tyres, or plastic residues is sufficient.

Waste produced during the course of normal business activity should be disposed of in an appropriate manner. Disposal by burning is not permissible and will be referred to the Environment Agency for investigation relating to the disposal of trade waste.

If you see dark smoke coming from a trade or industrial premises (including farms) or you suspect someone is burning trade or industrial waste and causing dark smoke please contact the Environmental Heath Section.