---
title: "CS 25.832 Cabin ozone concentration — CS-25 · Avioverse"
description: "The aeroplane cabin ozone concentration during flight must be shown not to exceed – (1) 0·25 parts per million by volume, sea level equivalent, at any…"
url: "https://avioverse.aero/regulations/easa/cs-25/subpart-d/cs-25-832"
---

# CS 25.832 Cabin ozone concentration

Large Aeroplanes (CS-25) · CS-25 · EAR revision 26 Jan 2023

IR Implementing rule

## CS 25.832 Cabin ozone concentration

(a) The aeroplane cabin ozone concentration during flight must be shown not to exceed –

(1) 0·25 parts per million by volume, sea level equivalent, at any time above flight level 320; and

(2) 0·1 parts per million by volume, sea level equivalent, time-weighted average during any 3-hour interval above flight level 270.

(b) For the purpose of this paragraph, “sea level equivalent” refers to conditions of 25° C (77° F) and 1 013·2 hPa (760 millimetres of mercury) pressure.

(c) Compliance with this paragraph must be shown by analysis or tests based on aeroplane operational procedures and performance limitations, that demonstrated that either –

(1) The aeroplane cannot be operated at an altitude which would result in cabin ozone concentrations exceeding the limits prescribed by sub-paragraph (a) of this paragraph; or

(2) The aeroplane ventilation system, including any ozone control equipment, will maintain cabin ozone concentrations at or below the limits prescribed by sub-paragraph (a) of this paragraph.

IR · CS 25.832 — CS-25 · ED Decision 2003/2/RM · CS-25 Easy Access Rules · EAR revision 26 Jan 2023

[All rules in SUBPART D – DESIGN AND CONSTRUCTION](https://avioverse.aero/regulations/easa/cs-25/subpart-d)

Consolidated from the EASA Easy Access Rules (revision 26 Jan 2023, extracted 13 Oct 2026) for convenience. Not the official publication — verify against the Official Journal of the European Union and the EASA publications before operational use.