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Halons

Bromofluorocarbons

SPRI Emission Reporting Threshold
1.00 Kg/yr Pollutant Emissions to Air
Disclaimer
This sheet is a generic summary, designed to give the reader a basic level of background information about the substance in question. Great care has been taken to represent as effectively and correctly as possible the broad range of (not necessarily consistent) information which is available from a variety of sources. The reader must accept therefore that this sheet has no legal status and cannot be relied upon in any legal proceedings. SEPA disclaims any responsibility or liability whatsoever for errors and omissions in this sheet.
What is it?
Halons are a family of chemicals similar to Chlorofluorocarbons (CFCs), but containing at least one atom of bromine. Like CFCs, Halons are very unreactive and stable, non-flammable and non-toxic. At room temperature, they are usually colourless gases or liquids which evaporate easily. Halons are also part of a group of chemicals known as the volatile organic compounds (VOCs).
What is it used for?
The use of Halons in developed countries has been phased out since the mid 1990's and since 2002 they are no longer permitted for use at all. The main use of Halons has been as fire suppressants in fire extinguishers. The various properties of the different Halons were utilised to produce specialist fire extinguishers for specific applications. Halon has also been used for research purposes, to track the circulation of species in the atmosphere. Halons have also been added to pesticide preparations, as propellants in sprays.
Where does it come from?
Halons have been released (usually in small amounts to the atmosphere) through their manufacture and use, mainly in fire extinguishers. There are not thought to be any natural sources of Halons to the environment.
How might it affect the environment?
Halons are unlikely to have any impact on the environment in the immediate vicinity of their release. As VOCs, they may be slightly involved in reactions to produce ozone, which can cause damage to plants and materials on a local scale. At a global level however, releases of Halons have serious environmental consquences. Their long lifetimes in the atmosphere mean that some end up in the higher atmopshere (stratosphere) where they can destroy the ozone layer, thus reducing the protection it offers the earth from the sun's harmful UV rays. Compared to other similar groups of chemicals, Halons are potent ozone depleters. Halons also contribute to Global Warming (through "the Greenhouse Effect"). Although the amounts emitted are relatively small, they have a powerful warming effect (a very high "Global Warming Potential").
How might exposure to it affect human health?
Halons enter the body primarily by inhalation of air containing halons, but can also enter by dermal contact with halons. The health effects associated with exposure to halons may vary depending on the particular chemical. Inhalation of air containing high levels of halons may result in breathing difficulties, chest tightness, dizziness, headache, accumulation of fluid in the lungs and unconsciousness. Dermal contact with halons in liquid form may cause skin irritation and frostbite. Eye contact can cause irritation. Halons are involved in the destruction of the stratospheric ozone layer resulting in increased exposure to UV radiation which is known to cause skin cancer. The International Agency for Research on Cancer has not designated halons as a group in terms of their carcinogenicity. However, exposure to halons at normal background levels is unlikely to have any adverse effect on human health.
What steps are being taken to limit the potential impacts?
Following the United Nations Montreal Protocol on Substances that Deplete the Ozone Layer and the related EC Regulation 2037/2000, the use of Halons has been phased out in the UK (including Scotland) and also in the majority of other developed countries. At an international level, Halons are regulated through the OSPAR Convention which protects the marine environment of the north-east Atlantic Ocean. Releases of Halons are also controlled through the UK Pollution, Prevention and Control (PPC) Regulations and, as VOCs, levels of Halons in air are regulated through the UK National Air Quality Strategy. The main international legislation regulating levels of VOCs such as Halons is the UN/ECE Convention on Long-Range Transboundary Air Pollution and the Basel Convention on the transboundary movement and disposal of hazardous wastes.