CA-CD1a · WHMIS Hazard statementMay form combustible dust concentrations in air

WHMIS, no GHS code · hazard statementPhysical

CA-CD1a is a WHMIS hazard statement from the Hazardous Products Regulations: “May form combustible dust concentrations in air”. The Regulations give it no code; CA-CD1a is the ID used on this site. It is used for Combustible Dusts, Category 1. Listed in US OSHA and Canada. Canada’s official French text is “Peut former des concentrations de poussières combustibles dans l’air”.

Maintained by Valenc. Data checked 2026-10-20.

Heading text: Canada HPR. Wording can differ by jurisdiction; see the table below.

Wording by jurisdiction

UN GHS Rev.11

Not in UN

GHS Rev.11 (2025), Annex 3

WHMIS element with no GHS code, not part of the UN GHS.

US OSHA HCS

Adopted

HCS 2024 · primarily GHS Rev.7, some Rev.8

May form combustible dust concentrations in air

Signal word: Warning

29 CFR 1910.1200 App. C, C.4.31 (label elements for OSHA defined hazards)

OSHA allows adding "[if small particles are generated during further processing, handling or by other means.]" when the dust hazard only arises from processing or handling (App. C, C.4.31).

EU CLP

Not adopted

EU_CLP_2025 · consolidated 1 Jul 2026

Not listed in EU CLP Annex III or IV.

Canada (EN)

No GHS code

WHMIS_2022 · GHS Rev.7 (Rev.8 for chemicals under pressure)

May form combustible dust concentrations in air

Signal word: Warning

HPR (SOR/2015-17) Schedule 5, Part 1, item 1(a)

Canada (FR)

No GHS code

WHMIS_2022 · SGH Rév.7, texte officiel

Peut former des concentrations de poussières combustibles dans l’air

Mention d’avertissement : Attention

HPR (SOR/2015-17) Schedule 5, Part 1, item 1(a)

Mexico (ES)

Not adopted

NOM-018-STPS-2015 · GHS 5th revised edition

Not listed in NOM-018-STPS-2015.

Hazard classes and categories

Combustible Dusts, Category 1

Canada HPR

FRPoussières combustibles : catégorie 1

Change in UN GHS Rev.11

Not part of the UN GHS, so Rev.11 does not apply.

Notes

Canada-specific HPR wording with no GHS code. The HPR does not assign a code; "CA-CD1a" is a lookup ID used on this page only.

Sources

Each cell in the table names the official table and page for CA-CD1a. Full citations, links and revision notes for UN GHS Rev.11, US OSHA, EU CLP, Canada and Mexico: Sources and revision notes.

These are regulatory phrases for labels and safety data sheets. Check them against the official source for your jurisdiction before use.