No open flame sign (P003)
A red ring and diagonal bar across a lit match means open flames are forbidden where the sign is posted, and smoking with them. It is sign P003 in ISO 7010.
Easily confused with
How to read it
ISO 7010 registers P003 with the meaning “No open flame; Fire, open ignition source and smoking prohibited”, one of the prohibition signs that ISO 3864-1 defines as indicating “a specific behaviour is forbidden”. Great Britain’s Safety Signs and Signals Regulations 1996 call the same sign “Smoking and naked flames forbidden”. Both cover more than a no-smoking sign: any open flame or ignition source.
Also searched as: no fire sign, no flame symbol, no naked flames sign, no open flames symbol, P003, smoking and naked flames forbidden.
These explain what each sign means and which standard sets it. What to do in a laboratory is set by the lab’s own rules, signs and trained staff; for a chemical, refer to its label and safety data sheet.
No open flame or no smoking
The two are separate signs in both systems. No smoking, P002 in ISO 7010, shows a cigarette and forbids smoking only. P003 shows a match and forbids open flames as well as smoking. The British regulations list them as two signs, “No smoking” and “Smoking and naked flames forbidden”. The University of Houston, a smoke-free campus, says no smoking is allowed in any of its labs, and that its door signs carry a smoking restriction where a regulation requires the sign to be posted.
Look-alikes
The GHS flame pictogram on chemical labels is a hazard pictogram, not a prohibition: Kansas State University’s safety office describes the GHS pictograms as outlined in red with a black image, a red diamond border where P003 has a ring and a bar.
Read next
- Next in Lab safety symbolsHot surface warning sign (W017)A yellow triangle with three wavy lines rising from a flat surface warns that a surface is hot. It is sign W017 in ISO 7010, and the same lines on equipment are the IEC “Caution, hot surface” symbol.
- No smoking (P002), the cigarette sign P003 extends to all open flames.Prohibition sign (red circle and slash)A red ring with a red diagonal bar over a black pictogram means that what the pictogram shows is forbidden, such as smoking or touching.
More lab safety symbols
The same shape elsewhere
Browse symbols drawn with circles or lines.
Sources
- ISO 3864-1:2011, Graphical symbols — Safety colours and safety signs — Part 1: Design principles for safety signs and safety markings (preview), ISO 3864-1:2011, International Organization for Standardization, preview via iTeh Standards, 3.7, Table 1
- ISO 7010:2011, Graphical symbols — Safety colours and safety signs — Registered safety signs (preview), ISO 7010:2011, International Organization for Standardization, preview via iTeh Standards, Table 1, Table 2
- The Health and Safety (Safety Signs and Signals) Regulations 1996, Schedule 1, SI 1996/341, legislation.gov.uk (UK Government), Part II, 3.1
- Laboratory Doorsigns, University of Houston Environmental Health and Safety, Information and Restrictions
- National Research Council Recommendations Concerning Chemical Hygiene in Laboratories (Non-Mandatory), Appendix A to 29 CFR 1910.1450, 29 CFR 1910.1450 Appendix A, U.S. Occupational Safety and Health Administration, Basic rules and procedures
- K-State Laboratory Signs, Kansas State University Environmental Health and Safety, GHS Pictograms
Researched, edited and approved by Rory Hansen before publishing. Last reviewed October 9, 2026. How we research
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