# A manufacturer of fire extinguishers previously used halon gases in their products. Explain why halons were considered harmful to the environment and describe what happened internationally to address this problem.

> OCR A-Level Chemistry B: Salters (H433) — OZ The ozone story · Explain · 5 marks

> Halon gases were widely used in fire extinguishers and fire suppression systems throughout the twentieth century. Like CFCs, halons contain halogen atoms bonded to carbon atoms.

## Mark scheme (5 marks)

1. Halons (like CFCs) release halogen/bromine or chlorine atoms/radicals in the stratosphere
2. These halogen atoms/radicals catalytically destroy ozone molecules
3. This thins/depletes the ozone layer, allowing more UV radiation to reach Earth's surface
4. Increased UV radiation reaching Earth causes harm to living organisms, e.g. increased risk of skin cancer or damage to ecosystems
5. International agreements (such as the Montreal Protocol) were made to phase out/ban the use of CFCs and halons

## Key terms

- [halons](https://www.gradenine.co.uk/glossary/halons)

## Related

- [Revision notes for OCR A-Level Chemistry B: Salters (H433)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-manufacturer-of-fire-extinguishers-previously-2c452165) · Published by Druglandscape Ltd.