Section 2 of the Clean Air Act 1993, (Prohibition of dark smoke from industrial or trade premises).
You must not burn at any time any material that will give rise to dark smoke, for example plastic and cable. BCC does not have to witness the burning of materials or an emission of dark smoke from your site to prove an offence has been committed.
If evidence is found at your site indicating that materials have been burnt that are likely to give rise to dark smoke, then this is deemed suitable evidence to prove an offence has been committed. Committing an offence under Section 2 may result in legal action and a fine of up to £50,000 or 6 months in prison.