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Control of Major Accident Hazards (COMAH)

The COMAH Regulations came into force on the 1 April 1999 and replace the previous Control of Industrial Major Accident Hazards (CIMAH) Regulations. Military establishments have similar regulations known as Major Accident Control Regulations (MACR).

COMAH Regulations apply mostly to the chemical industry, but are also applied to some storage activities (explosives and nuclear sites), and other industries where threshold quantities of dangerous substances, as identified in the Regulations, are kept or used.

The Health and Safety Executive and the Environment Agency are responsible for the enforcement of the COMAH Regulations. These authorities are known as the 'Competent Authority'.

There are two classifications under the Regulations:

Upper Tier Sites
Lower Tier Sites

Upper Tier Sites have an off-site plan which is prepared by the Local Authority and tested every three years. Hampshire Fire and Rescue Service carry out a practical exercise on the Upper Tier COMAH Sites every three years.