The ozone layer: what it is and why it matters
Short answer
Ozone is a molecule of three oxygen atoms (O3). Most of it sits in the stratosphere, roughly 15 to 30 km up, where it absorbs much of the Sun's ultraviolet (UV) radiation. [S1][S2]
Key points
- Good up high, bad nearby: near the ground, ozone forms from vehicle and other pollution and is a pollutant. [S1]
- UV bands: UVA is not absorbed by ozone, UVB is mostly absorbed, UVC is fully absorbed. [S2]
- Damage: human-made ozone-depleting substances have thinned the layer. [S2]
Claims
- id: C1 claim: Ozone is a gas made of three oxygen atoms. source: S1 evidence: "Ozone is a gas made up of three oxygen atoms (O3)."
- id: C2 claim: Ozone protects life on Earth from the Sun's UV radiation. source: S1 evidence: "Ozone protects life on Earth from the Sun’s ultraviolet (UV) radiation."
- id: C3 claim: UVA is not absorbed by ozone. source: S2 evidence: "UVA is not absorbed by ozone."
- id: C4 claim: Most atmospheric ozone is concentrated in a stratospheric layer. source: S2 evidence: "Most atmospheric ozone is concentrated in a layer in the stratosphere"
Sources
- [S1] Nasa Ozone Watch: Ozone facts. NASA. https://ozonewatch.gsfc.nasa.gov/facts/SH.html . License: US government work, public domain. Accessed 2026-11-04.
- [S2] Basic Ozone Layer Science. US EPA. https://www.epa.gov/ozone-layer-protection/basic-ozone-layer-science . License: US government work, public domain. Accessed 2026-11-04.
License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).
License: CC-BY-4.0 · Summary by iinventedlight (AI-assisted). Sources: NASA, Nasa Ozone Watch: Ozone facts, US government work, public domain; US EPA, Basic Ozone Layer Science, US government work, public domain.
Cite this
iinventedlight. 2026. "The ozone layer: what it is and why it matters." iinventedlight Library, iil:note:anv9nwde, version of 2026-11-04. https://iinventedlight.com/library/notes/ozone-layer/. License: CC-BY-4.0.
@misc{iil_note_anv9nwde,
author = {{iinventedlight}},
title = {{The ozone layer: what it is and why it matters}},
howpublished = {iinventedlight Library},
year = {2026},
date = {2026-11-04},
url = {https://iinventedlight.com/library/notes/ozone-layer/},
note = {Permanent ID iil:note:anv9nwde. License: CC-BY-4.0.},
}Spotted a mistake? Use the MCP feedback tool or email hello@iinventedlight.com.
For language models and agents: start at /llms.txt. This page in Markdown: /library/notes/ozone-layer.md.