NAMOS 1990: HSE Dangerous Substances Site Notification

Regulatory citation: Dangerous Substances (Notification and Marking of Sites) Regulations 1990 (SI 1990/304)

What Are the NAMOS Regulations?

The Dangerous Substances (Notification and Marking of Sites) Regulations 1990, known as NAMOS, require the person in control of a site holding 25 tonnes or more of dangerous substances in total to notify the fire and rescue service and the enforcing authority, and to put warning signs at the site entrances. HSE explains that the regime is based on dangerous goods as classified for carriage under the Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations 2009.

Since 6 April 2013, NAMOS also requires sites holding 150 tonnes or more of relevant ammonium nitrate mixtures to notify the fire and rescue service.

Why NAMOS Matters

Firefighters arriving at an incident need to know what is stored on site. Notification lets the fire service plan its response in advance, and access signs warn crews before they enter.

Core Requirements

1. Work Out Your Total Quantity (Regulations 2 and 4)

The duty applies when 25 tonnes or more of dangerous substances are present at any one time. Substances in vehicles, vessels or containers count if they are used for storage on the site. Substances being transported and fuel in vehicle tanks do not count.

2. Check the Exceptions (Regulation 3 and Schedule 1)

The Regulations do not apply to dangerous substances buried or deposited in the ground as waste, to substances that are dangerous only because they are radioactive, to explosives, or to certain aerosol dispensers. Some sites already covered by other notification or licensing regimes are excluded from the notification duty, and some are excluded from marking. Schedule 1 sets out the full list.

3. Notify in Writing Before Reaching 25 Tonnes (Regulation 4)

The person in control must make sure 25 tonnes or more is not present unless written notice has been given to the fire authority and the enforcing authority for the site. Schedule 2 lists the details: the notifier's name and address, the site's full postal address, a description of the business, the classifications of dangerous substances present and the date the 25-tonne total is expected to be reached.

4. Notify Changes Straight Away (Regulation 4(2)–(3))

Both authorities must be told forthwith of any change in the classifications notified, or if dangerous substances cease to be present or drop below 25 tonnes other than temporarily. If quantities later rise back to 25 tonnes or more, a fresh notification is needed.

5. Notify Ammonium Nitrate Storage

HSE guidance explains that from 6 April 2013, sites holding 150 tonnes or more of relevant ammonium nitrate mixtures, where nitrogen content exceeds 15.75% by weight, must notify the fire and rescue service only. Signs are not required for ammonium nitrate mixtures alone. Ammonium nitrate products listed as dangerous goods for carriage still count toward the 25-tonne total.

6. Display Access Signs (Regulation 5)

Whenever 25 tonnes or more is present, warning signs must be displayed at places that will warn firefighters before they enter the site in an emergency, usually the entrances. The sign uses the general dangerous substance hazard symbol set out in the Regulations.

7. Mark Locations if Directed and Maintain Signs (Regulations 6–7)

An inspector can direct the person in control to put signs at specific locations within the site, showing the hazard symbol and text for the class of substance stored there, or a mixed hazards sign. All signs must be kept clean and free from obstruction so far as reasonably practicable.

Common Compliance Approaches

Keep a Live Inventory

Track quantities and classifications of stored substances so you know when you approach 25 tonnes and when classifications change.

Use the NAMOS Form

HSE provides a notification form that records the required details. Send it to both the fire and rescue service and the enforcing authority.

Invite the Fire Service

Many sites arrange a familiarisation visit so local crews know the layout, storage areas and access points.

Example: NAMOS in Practice

A chemical distributor opens a new warehouse expecting to hold about 60 tonnes of flammable liquids, corrosives and toxic substances. Before the first deliveries, the site manager sends a NAMOS notification to the local fire and rescue service and the local authority enforcing officer, listing each classification. Warning signs go up at both gates. When the company later starts storing oxidising agents, it notifies the change straight away.

Related regulations: DSEAR explosive atmospheres, COSHH hazardous substances, EPA Tier II reporting.

Note: This summary reflects the law as it applies in Great Britain, enforced by the Health and Safety Executive (HSE) and other enforcing authorities. Northern Ireland has equivalent but separate legislation. Always check the current legislation and HSE guidance.

Frequently Asked Questions

What is the NAMOS threshold?

NAMOS applies when a site holds 25 tonnes or more of dangerous substances in total at any one time. Separate notification applies to 150 tonnes or more of relevant ammonium nitrate mixtures.

Who do I notify under NAMOS?

For dangerous substances, notify both the local fire and rescue service and the enforcing authority, which is HSE or the local authority depending on the type of site. For ammonium nitrate mixtures alone, only the fire and rescue service needs to be notified.

Do temporary drops below 25 tonnes need to be notified?

No. Only a reduction below 25 tonnes or cessation that is not temporary must be notified. Temporary, foreseeable fluctuations in stock do not count.