Guide

Preventing air pollution

Last updated: 8 December 2017

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'.

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

Chimney and boiler restrictions

You mustn't release dark smoke from your premises, including from:

  • chimneys serving furnaces
  • fixed boilers or industrial plants, whether they're attached to buildings or not

There are some exemptions if emissions won't damage health or cause a nuisance.

Preventing air pollution
Dark smoke