This page provides access to information relating to the Control of Major Accident Hazards Regulations 1999 (COMAH) which came into force on 1 April 1999. These Regulations implemented the Seveso II Directive (except for the land use planning requirements), and replaced the Control of Industrial Major Accident Hazards Regulations 1984 (CIMAH). Amendment Regulations, bringing into force the requirements of an Amendment Directive broadening Seveso II, are due to come into force on 30 June 2005. COMAH applies mainly to the chemical industry, but also to some storage activities, explosives and nuclear sites, and other industries where threshold quantities of dangerous substances identified in the Regulations are kept or used. The Regulations apply at two thresholds, the lower-tier and top-tier depending upon the quantity of dangerous substances stored. If the lower-tier threshold is equalled or exceeded, operators must notify the Competent Authority. The operator must also prepare a Major Accident Prevention Policy (MAPP). If the top-tier threshold is equalled or exceeded, operators must comply with additional requirements to provide a Safety Report and have an on-site emergency plan. Local authorities must also prepare an off-site emergency plan for each top-tier site. COMAH is implemented by a joint Competent Authority consisting of the Health and Safety Executive (HSE) and in Scotland, the Scottish Environment Protection Agency. The Competent Authority publishes the majority of its guidance on the HSE web-site. The links below contain further information on COMAH and what to do if the Regulations apply to you. HSE: http://www.hse.gov.uk/comah/ Environment Agency: http://www.environment-agency.gov.uk/business/444217/444663/comah/?version=1&lang=_e Defra: http://www.defra.gov.uk/environment/chemicals/accident/" Major Accident Hazards Bureau (MAHB) European Commission: http://mahbsrv.jrc.it/