Prohibition Signs in the Workplace: Your Complete Guide to AS1319 Compliance

The red circle with a diagonal line is one of the most universally understood symbols in workplace safety. Prohibition signs communicate a clear, non-negotiable message: do not do this. Whether it is a no smoking sign at a hospital entrance or a no unauthorised access sign at a construction site, these signs play a critical role in preventing injuries and supporting regulatory compliance across Australian workplaces.

If you are responsible for workplace health and safety, understanding how prohibition signs work under Australian Standard AS1319 is essential. This guide covers design requirements, placement strategies, and the industries that rely most heavily on prohibition signage.

What Are Prohibition Signs Under AS1319?

Australian Standard AS1319 (Safety Signs for the Occupational Environment) classifies safety signs into several categories, each with a distinct colour scheme. Prohibition signs are defined by their red circular band with a diagonal line across a white background. The pictogram inside depicts the action that is prohibited.

Unlike warning signs, which alert people to a hazard, or mandatory signs, which instruct people to take a required action, prohibition signs tell people what they must not do. A warning sign with a yellow triangle might tell workers a forklift operates in the area. A mandatory sign with a blue circle might require hard hats. A prohibition sign tells people they must not enter, must not smoke, or must not use a mobile phone.

Common Types of Prohibition Signs

Certain prohibition signs appear far more frequently than others. Understanding the most common types helps safety managers identify gaps in their current signage.

No Smoking signs are the most widespread prohibition sign in Australia. Legislation in every state and territory restricts smoking in enclosed public places and workplaces. Failure to display appropriate no smoking signs can result in fines.

No Entry and No Unauthorised Access signs control movement within a workplace. These signs restrict access to hazardous areas, plant rooms, electrical switchboards, and secure zones. Pairing these with security signs strengthens access control throughout a site.

No Mobile Phones signs are common in hospitals, fuel stations, laboratories, and areas where electronic interference could create safety risks or an ignition source near flammable materials.

Do Not Operate signs are used during maintenance and lockout/tagout procedures. These signs prevent workers from activating machinery while colleagues are performing repairs or inspections.

No Photography signs protect sensitive areas where images could compromise security, intellectual property, or personal privacy. They are common in defence facilities, data centres, and some healthcare settings.

How Prohibition Signs Differ from Warning and Mandatory Signs

One of the most common mistakes in workplace signage is using the wrong category of sign. Each category under AS1319 serves a specific communication purpose, and mixing them up creates confusion that undermines safety.

Prohibition signs (red circle, diagonal line) tell people what they must not do. They forbid an action. The message is absolute: this behaviour is not permitted here.

Warning signs (yellow triangle) alert people to a potential hazard without forbidding an action. A warning sign near a chemical storage area indicates the hazard is present but does not tell people to stay out.

Mandatory signs (blue circle) instruct people to perform a required action, such as wearing hearing protection or safety glasses.

Regulators expect workplaces to use the correct sign category for each situation. A prohibition sign where a warning sign should be, or vice versa, suggests a lack of understanding of safety obligations.

Industries That Rely Heavily on Prohibition Signage

While every workplace benefits from appropriate prohibition signs, certain industries depend on them more than others.

Healthcare and aged care facilities use prohibition signs extensively. No smoking signage is mandatory across hospital grounds in most jurisdictions, while no mobile phone signs protect sensitive medical equipment and no entry signs restrict access to sterile zones.

Construction and building sites are among the most sign-intensive workplaces in Australia. Prohibition signs control access to excavation zones, crane operating areas, and high-voltage installations. They complement the broader suite of construction signs and building site signs that manage safety on these sites.

Hospitality and food service businesses rely on prohibition signage to manage hygiene, fire safety, and access control. No smoking signs are legally required in and around food preparation and dining areas, while staff-only areas require no unauthorised access signs.

Manufacturing and warehousing facilities use prohibition signs around dangerous machinery, chemical stores, and restricted operational zones. No pedestrian signs in forklift areas and no naked flame signs near flammable storage are common examples.

Placement and Visibility Requirements

A prohibition sign that cannot be seen fails to serve its purpose. AS1319 provides guidance on sign placement, and workplace health and safety regulations reinforce the requirement for signs to be clearly visible.

Prohibition signs should be placed at decision points: the locations where a person chooses whether to proceed with the prohibited action. For a no entry sign, this means positioning it at the entrance to the restricted area, not inside. For a no smoking sign, it should be visible before a person reaches the designated boundary.

Sign size matters as well. AS1319 specifies minimum viewing distances for different sign sizes. A small sign appropriate for a doorway would be inadequate for a large warehouse or outdoor area where it needs to be read from 20 metres or more.

Environmental factors also influence placement. Signs exposed to weather, UV radiation, chemicals, or physical impact need durable materials. Regular inspections should check for fading, damage, or obstruction that could reduce effectiveness.

Conducting a Prohibition Sign Audit

Reviewing your current prohibition signage is a practical step most workplaces can complete in a single day. Walk through every area of your site and note where prohibited actions exist, whether currently signed or not.

Check each existing sign for correct design (red circle, diagonal line, white background), appropriate size for viewing distance, and physical condition. Replace any signs that are faded, damaged, or non-compliant. Identify areas where new prohibition signs are needed but not yet installed.

Document your findings and create a maintenance schedule. Signs require regular inspection and replacement as part of your ongoing safety management system.

Key Takeaways

• Prohibition signs use a red circle with diagonal line to indicate forbidden actions under AS1319
• They differ from warning signs (yellow triangle, hazard alert) and mandatory signs (blue circle, required action)
• No smoking, no entry, no mobile phones, and do not operate are the most common prohibition signs
• Healthcare, construction, hospitality, and manufacturing rely heavily on prohibition signage
• Correct placement at decision points and appropriate sizing for viewing distance are essential
• Regular audits help maintain compliance and identify signage gaps