# Zone 21 — Certification marks and hazardous-area classifications: cross-market equivalences

For Zone 21, market / system is IEC / ATEX; meaning is Dust likely during normal operation, recorded from its source on 2026-08-11.

- **Designation:** Zone 21 _(verified: appears in the quote below)_
- **Market / system:** IEC / ATEX
- **Meaning:** Dust likely during normal operation _(verified: appears in the quote below)_

## What the source says

> Zone 21 | Dust likely during normal operation

## Source

- https://www.inframena.com/hazardous-area-classification-equivalency-guide/

Last verified: 2026-08-11. Review by: 2027-08-11.
Part of [Certification marks and hazardous-area classifications: cross-market equivalences](https://referencesource.org/certification-standards-equivalence/).