3. Nomenclature of 1953

The nomenclature of establishments classified as dangerous, unhealthy or inconvenient, appended to décret n° 53-578 du 20 mai 1953 , provides for an alphabetical classification of establishments. This led to a shift from the classification of establishments to the installations or activities that make up the establishment, a shift that was confirmed by loi du 19 juillet 1976 on installations classified for environmental protection. The latter law applies to any activity or operation, regardless of its context or purpose.

The four-column nomenclature structure has been defined.