Chemical Disasters or Accidents

The following definitions have been adopted in various existing Indian laws.

  • "chemical accident" means an accident involving a fortuitous, or sudden or unintended occurrence while handling any hazardous chemicals resulting in continuous, intermittent or repeated exposure to death, or injury to, any person or damage to any property but does not include an accident by reason only of war or radio-activity;
  • "major chemical accident" means, - an occurrence including any particular major emission, fire or explosion involving one or more hazardous chemicals and resulting from uncontrolled developments in the course of industrial activity or transportation or due to natural events leading to serious effects both immediate or delayed, inside or outside the installation likely to cause substantial loss of life and property including adverse effects on the environment;
  • "Major Accident Hazards (MAH) Installations" - means, isolated storage and industrial activity at a site, handling (including transport through carrier or pipeline) of hazardous chemicals equal to or, in excess of the threshold quantities specified in column 3 of Schedule 2 and 3 respectively of MS and IHC rules 1989.

Sources of the above disasters and accidents

The above accidents as defined in point 2.0 may happen to any one of the following "industrial activity"

  • carried out in an industrial installation referred to in Schedule 4 involving or likely to involve one or more hazardous chemicals; Schedule -4 is of MS and IHC rules 1989 and is shown in appendix 2;
  • on-site storage or on-site transport which is associated with that operation or process as the case may be;
  • isolated storage;
  • pipelines.

Types of major chemical/industrial hazards

In addition to loss of life, the major consequences of chemical disasters include impact on livestock, flora/fauna, the environment (air, soil, water) and losses to industry as shown in Figure 1. Chemical accidents may be categorised as a major accident or a disaster depending upon the number of casualties, injuries, damage to the property or environment. A major accident is defined in the Manufacture, Storage and Import of Hazardous Chemicals (MSIHC) Rules, 1989, issued under the Environment (Protection) Act, 1986, whereas 'disaster' is defined in the DM Act, 2005.

Immediate, Short-term and Long-term Effect

Major industrial hazards are generally associated with the potential for fire, explosion or dispersion of toxic chemicals and usually involve the accidentally release of chemicals from containment. Accidents involving major hazards could include:

  • Leakage of flammable material, mixing of material with air, formation of flammable vapour cloud to a source of ignition, leading to a fire or an explosion affecting the site and possibly a populated area.
  • Leakage of toxic material, formation of a toxic vapour cloud and drifting the cloud, affecting directly the site and possibly populated area.
  • Depending upon the state of released chemical, cause and on its consequences, the major hazards in chemical process industry are classified as:
  • Fire
  • Explosion -Toxic release


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