Dispelling the myths about fog

General questions

Security fog stops crime. It is a loss-prevention/crime deterrent method designed to minimise and even completely negate theft during a break-in. As the name suggests, it is a wall of smoke produced almost instantly that acts as a barrier.

Each year police receive over 100,000 genuine alarm calls from commercial premises under attack by thieves. Theft from break-ins, burglaries, ram raids, smash-and-grabs and hold-ups make up a significant portion of the £2bn a year that is lost by businesses to retail crime.

No. The fog is made up of water, glycol and glycerine. The glycol and glycerine we use are food-grade and are present in everyday products such as toothpaste, pharmaceuticals and even chewing gum. It is completely harmless, has no adverse effect and will not contaminate.

That’s the big question. It all depends on your needs. A fully integrated multi-device system with strobes and sounders will cost significantly more than a single machine.

It also depends on the size of the area you are trying to protect, how many machines you will need, and the machine model. A large area such as a warehouse will require several machines to protect it.

It’s also important to consider the machine placement – we recommend that you focus the fog on the assets you need to protect.

An advanced technique to help fog go further is to use a ducted system – the generator fires into a small channel of plastic pipes with outlets staggered throughout that distribute the smoke over a larger area.

Across the sector, there is a wide range of machines to choose from all with varied benefits and outputs. Talk to your sales representative about the most cost-effective way to protect your property.

If the Smoke Screen is installed correctly then there is no possibility of damage.

No, you do not have to fill the whole room with fog. Localised protection can be achieved with the correct machine placement, and this is the most effective way to use security fog. Smoke Screen fog is very persistent, and with the smallest particle size in the industry means our fog travels at a speed of just 0.9mm per hour in an unventilated room.


It is best to mount a Smoke Screen machine so that it is directed at what you are trying to protect – then when the Smoke Screen activates, the first thing it protects is the asset.

Where possible, we recommend positioning each Smoke Screen so it fires downwards, thereby creating a mushroom effect when the fog hits the floor, providing even more coverage of the risk area. However, they can be installed at almost any angle and attitude.

You can install them yourself, and there are plenty of mounting brackets and fixings available. However, we have a team of registered installers who are trained to install the machines and have the knowledge to recommend the most effective locations and optimum hang heights.

Yes, Smoke Screens are ideal for protecting large warehouses and retail spaces. For these spaces, we advise using multiple machines.

99% of the time, yes – Smoke Screens are designed to connect to existing alarm systems. They require a set/unset signal from the alarm system, as well as a trigger signal. The inputs into the Smoke Screen are volt-free contacts.


Make sure you and anyone else in the area are safe. If your Smoke Screen is connected to a monitoring system, the station will be notified. If not, call 999.

If you are in the area when the Smoke Screen activates, drop to the floor and crawl to a designated safe area.

Remain where you are until visibility starts to return, then make your way to the exit and wait for the police.

If the activation happens out of hours, wait until the system has completed its pre-set operating period and smoke protection has ceased. Do not try and enter the affected area.

Look for obvious signs of forced entry. If there are any, or if you believe criminals are on the premises, wait for the police to arrive.

Where there are no signs of forced entry, open the external doors and wait as the fog starts to vent – this might take 10-15 minutes. Keep watch for intruders, who may be hidden.

As visibility returns, you can open more doors and windows to speed up venting.

Check the fluid levels in each machine and replace if necessary.

No. Depending on the machine, our fluid will usually last between 4-8 activations. The Smoke Screen system will state when the machine has 'Low Fluid' or 'Empty Fluid'.

Typically, Smoke Screen machines are set up to provide protection for up to 45 minutes each time they are activated. This is a combination of the initial activation of 30-60 seconds, followed by re-triggers for up to 45 minutes, or until the machine is deactivated. The fog will hang in the air for approximately an hour, so the area is still protected if the thieves come back.

All vulnerable parts of the machine are protected, so if any of the machine's covers are unscrewed, or if a machine is removed from the wall, a signal will be sent to the alarm system to raise the alert.

Smoke Screens are typically mounted high up, meaning they cannot be easily accessed. In cases where they are accessible, tampering has always proved ineffective. The typical methods used by thieves to attempt to block a Smoke Screen include sticking tape over the nozzle, inserting a nail into the nozzle, and taping cardboard or plastic over the machine. In all of these instances, the machine is so powerful that it simply ejects the obstruction and carries on as normal. End-users may also notice the activity or obstruction and remove it.

All Smoke Screen machines have a battery back-up system that means they will still activate. Depending on the machine, battery back-up ranges from 30 minutes to 1.5 hours!


Concept Smoke Screen have product and public liability cover that covers all eventualities, and we have never had a successful claim against us. All end-users are also required to have the machines regularly maintained and to display security fog warning stickers.

In general, the police regard the use of Smoke Screens as a positive move against intrusive criminals. Many Crime Prevention Officers are happy to recommend the system and the National Police Chief's Council (NPCC) have produced guidelines governing the installation and operation of Smoke Screens.

Fire brigade personnel appreciate the need for such systems and the Chief Fire Officers Association (CFOA) has produced a set of guidelines for national brigades to reference.

Insurers in many countries now recommend security fog.

That will depend on the individual insurer. It is not unheard of for a discount to be offered, but you will need to discuss it with your own insurers.

Yes, there are. Smoke Screens comply with BS EN50131-8:2019 Alarm Systems-Intrusions and Hold-up systems; Security fog devices, which was developed by the British Standards Institute and the European CENELEC Standards Organisation.

We also comply with security fogging Standard IEC 62642-8:2011, a Geneva-based international standard used around the world.