# ozone

/ˈoʊˌzoʊn/ (US) · /ˈəʊzəʊn/ (UK)

Source: https://englishreference.com/word/ozone
Updated: 2026-08-08

## Senses

### 1. atmospheric gas

noun · CEFR B2 · Technical

a form of oxygen that forms a layer high in the sky, protecting the Earth from the sun's dangerous rays.

For teachers: an allotrope of oxygen (O₃) found in the stratosphere that absorbs most of the sun's ultraviolet radiation.

- Scientists are worried about the hole in the ozone layer over the Antarctic.
- The Montreal Protocol was designed to protect the ozone layer by phasing out the production of substances responsible for its depletion.

Usage: Usually used as an uncountable noun; frequently appears in the compound 'ozone layer'.

### 2. fresh seaside air

noun · CEFR C1 · British English · Informal

fresh, clean air, especially the kind you breathe when you are at the beach.

For teachers: fresh, bracing air, particularly that found at the seaside and associated with the smell of the ocean.

- We went for a walk along the cliffs to breathe in some of that healthy ozone.
- After a week in the smoggy city, the crisp seaside ozone was a welcome relief for the travellers.

Teaching tip: This sense is based on a historical misconception that the smell of the sea was ozone; it is now used figuratively to mean 'bracing air'.

### 3. to treat with gas

verb · CEFR C2 · Technical

to clean or treat something using ozone gas.

For teachers: to subject to the action of ozone, typically for the purpose of purification or bleaching.

- The company uses a special machine to ozone the water and kill bacteria.
- The facility began to ozone the wastewater as a final stage of treatment to ensure all organic contaminants were neutralised.

Usage: A transitive verb requiring a direct object.

## Examples

- The ozone layer protects us from the sun.
- Scientists monitored the hole in the ozone layer to see if the new environmental laws were working.
- While stratospheric ozone is essential for filtering ultraviolet radiation, ground-level ozone is a primary component of urban smog and can cause significant respiratory distress in vulnerable populations.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.