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The Dangerous Substances (Notification and Marking of Sites) Regulations


The Dangerous Substances (Notification and Marking of Sites) Regulations (NAMOS) has the principal aim of ensuring that firefighters arriving at an incident are warned of the presence of dangerous substances.

The NAMOS Regulations are based on the Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations 2009 (CDG). It is a legal requirement under the NAMOS Regulations to notify the fire and rescue service (FRS) and the enforcing authority for the Health and Safety at Work Act (e.g. the HSE /local authority) about any site containing either of the following:

  • A total quantity of 25 tonnes or more of dangerous substances.

  • 150 tonnes or more of relevant ammonium nitrate mixtures (defined as ammonium nitrate and mixtures containing ammonium nitrate, where the nitrogen content exceeds 15.75% of the mixture by weight). Ammonium nitrate mixtures which carry an oxidising agent symbol are deemed for the purposes of NAMOS to be a ‘dangerous substance’.

The CDG Regulations are based on a European Agreement concerning the International Carriage of Dangerous Goods by Road (known as ADR) which contains a list of dangerous substances.  NAMOS is concerned with all materials and products that carry a hazard warning symbol which in broad terms are categorised as follows:

  • Non-flammable compressed gases

  • Toxic gases

  • Flammable gases

  • Flammable solids

  • Spontaneously combustible substances

  • Substances which, in contact with water, emit flammable gas

  • Oxidising substances

  • Organic peroxides

  • Toxic, corrosive or harmful substances

  • Other dangerous substances



The main objectives of NAMOS are to ensure that:

1.      Fire authorities and enforcing authorities are in possession of information which will help them in defining priorities for carrying out inspection programmes for their separate purposes.

2.      Firefighters arriving at an incident are warned of the presence of dangerous substances and of the need to make use of the information previously gathered for firefighting purposes.



The background to NAMOS is such that the following notification regimes apply:

Nature of materials stored

Notify local Fire & Rescue Service

Notify enforcing authority (HSE/LA)

Mark site entrance with warning sign

A and B




A only




B only




Neither A nor B






A - 25 tonnes or more of dangerous substances.

B - 150 tonnes or more of ammonium nitrate mixtures, where the nitrogen content exceeds 15.75% of the mixture by weight (and the ammonium nitrate mixture is not a ‘dangerous substance’).

All sites having present at any one time a quantity of 25 tonnes or more of dangerous substances must display signs bearing the exclamation mark symbol, as defined by BS 5378 (as superseded by BS 5499 Part 5 2002), at such places as will give adequate warning to firefighters before entering the site in an emergency. The inspecting officer may instruct the person in control of the site to also display safety signs at such locations within the site as they deem necessary. The intention of these signs is to give firefighters information of significant hazards within a site.

Example of an access sign

Examples of location signs


Consultants should be aware of the requirements of the NAMOS Regulations and, where appropriate, suitable enquiries should be made in order to ascertain compliance in respect of site notification and marking. Where a site falls under NAMOS, mention of this fact, referring to the full name of the Regulations (rather than using the acronym) should feature in the survey report.

When conducting surveys of farms, care should be taken concerning the storage and handling of ammonium nitrate fertilisers. The tonnage and nature of the materials may on occasions, be such that the NAMOS Regulations apply. This may possibly be the case when dealing with a large combine, or where bulk purchases are made beyond immediate needs.



Dealing specifically with ammonium nitrate, information on the hazards and precautions is contained in the HSE publication INDG230: Storing and Handling of Ammonium Nitrate available, together with other sources of reference via the HSE webpage -

When referring to INDG230, it should be noted that it is no longer totally up to date as far as it relates to current legislation. The Notification of Installations Handling Hazardous Substances Regulations has been revoked, superseded by the amendment of the NAMOS Regulations 2013. Also, the Control of Industrial Major Hazards Regulations (CIMAH) has been superseded by the Control of Major Accident Hazards Regulations (COMAH).

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