Hazardous materials signs indicate that there are materials like flammable liquids or toxic substances in the area. These signs tell workers and emergency responders how careful they need to be and what kind of danger they are dealing with.

No, they are not the same. DOT placards are used when hazardous materials are being transported and they follow DOT regulations under 49 CFR. Hazardous materials signs fall under OSHA and are used in workplaces to identify areas and equipment that have chemical hazards. Both types of signs tell us about chemical hazards. They are used in different situations and follow different rules.

There are rules from OSHA that cover hazard communication and chemical identification. OSHA 29 CFR 1910.1200 is one of these rules. Another rule is OSHA 29 CFR 1910.145, which covers accident prevention signs and tags. If a facility handles large quantities of certain chemicals they may also need to follow EPA 40 CFR Part 68. The NFPA 704 rule gives guidance on hazard rating systems.

Any facility that stores or uses hazardous materials needs these signs. This includes chemical plants, refineries, warehouses, laboratories and fuel storage areas to warn workers and emergency responders.

At the least the sign should clearly say what the hazard is and what kind of danger it poses. It should also tell workers if there are any restrictions on accessing the area. Some signs also include symbols or ratings to give workers and emergency responders more actionable information at a glance.

Sometimes a general hazardous materials sign is fine for a mixed storage area. If the chemicals are very different, it is better to have individual signs for each substance. This way workers are less likely to make mistakes.

There is no minimum distance, but the sign should be easy to read from the point where a worker would normally stop before entering the area. For large storage areas a bigger sign that can be read from further away is a good idea.