The modern approach to pollution control is to license those activities which are most likely to produce pollution. The operator of a process does not have to be caught polluting to commit an offence. Operating a ‘prescribed’ process without the required licence is an offence in itself, as is failure to comply with the conditions imposed by a licence.
The problem for the process operator is that they are obliged to find out if their business is subject to this kind of law. (Under different Acts of Parliament and Regulations, such consent regimes are known as ‘licences’, ‘permits’ or ‘authorisations’(see emissions to air).