The distribution centres of leading UK supermarkets and retailers have been classifying spaces where underarm deodorants or other aerosols are stored as Zone 2 areas. Darren Boiling explains why this has been a logical step for the safety of their employees, neighbours and the environment.

There is no doubt that products contained in aerosol cans are often extremely flammable. Common examples found in the home include furniture polish, underarm deodorants, cleaning products, hairspray, adhesives, paints, and many more. These are all labelled extremely flammable and found across the retail sector from supermarkets, DIY stores and discount retailers.

From a single flammable aerosol spray…

Scientifically, even when the volume of flammable material in each spray can is relatively small, it is sufficient to complete the ignition triangle, as typical propellants – butane, isobutane and propane are all flammable.  Being under pressure, the resultant burst of flame can quickly spread to other cans.

….to a warehouse full of flammable aerosols

From the relatively small volume of propellant in an individual can, consider the hundreds of cylinders on a pallet, then the fact that a warehouse may have thousands of pallets. Scaled up, a distribution warehouse could be storing as many as one million flammable aerosols under one roof!

In volume, this is a lot of flammable material which requires special measures particularly under the COMAH (Control of Major Accident Hazards) regulations and the associated tier rating of the facility.

Classifying aerosol storage as a hazardous area

So, there is clearly a risk of fire and explosion when aerosols are stored in volume; warranting consideration to the safety of people, the business, and the environment in the event of an incident happening.

In addition to COMAH, a DSEAR assessment under the ATEX Directive is required, as we have established that flammable products are being handled. This assessment will determine if formal classification into Zones is required.  Here is where the grey area comes in regarding how sources of release and the consequences are assessed.

Some assessments conclude not to formally classify the areas as the consideration focuses on a possible release being from just a few aerosols rather than the cascading effect from just a single release being ignited.  Other assessments do classify the areas, typically as zone 2.

Sadly, accidents have happened at aerosol warehouses where cans have been ignited due to being pierced, crushed or run over during stock movements and the released flammable gas ignited by the fork truck. These are the more common sources of release, it has also been recorded where an incident occurred from the release of the cans content, not through catastrophic failure of the can structure, but through poor stacking pressing on the top of the can deep in its storage location. Not known to anyone until an unprotected truck drove by igniting the gas cloud.


Incident reports show how quickly a single incident can cascade into a significant fire as the surrounding aerosols burst and become projectiles spreading the fire around the warehouse; far more severe than a “small nuisance fire” put forward in a discussion regarding the risk assessment.

The fire and possible explosion pose a human risk, environmental pollution hazard, risk to neighbouring businesses along with product losses, disruption to the supply chain, and it has an effect on the brand.

What to do if you handle aerosols in bulk

The message is really clear for 3rd party logistics firms, transport companies, and businesses like supermarkets or aerosol manufacturers where aerosols are handled in bulk.  A COMAH and DSEAR (in the UK) / ATEX 1999/92/EC risk assessment should be performed to establish baseline requirements (COMAH Tier and if ATEX zoned areas are mandated).

Human error should be considered which may increase the likelihood of accidental release and also take historic evidence from previous incidents into account during the assessment.

The risks are real.   

Where forklifts, VNA, or other warehouse equipment is used, if the area is classified Zone 2, the materials handling equipment should be ATEX compliant  in order to prevent an ignition in the event of propellant release.

Furthermore, the use of active gas detection on the forklift is advisable to alert the operator to the release of flammable material to help find the cause and make the operation safe.

Do I need full explosion protection?

If the DSEAR assessment doesn’t classify Zone 2 hazardous areas, you are not obliged to use explosion protected trucks, but what are the options?

Using standard trucks in this case is not recommended at all.

You may still opt to use ATEX equipment as it clearly addresses all ignition sources, or you could look to follow Guidance documents from relevant industry groups.

Guidance documents can be useful to provide an overview of requirements and may even suggest “Best Practice” ideas for consideration.  Unlike formal standards, they don’t provide a presumption of conformity on a legal basis and may still require further interpretation to establish explicit actions when the specific application is considered.

From our experience, the operator of the warehouse is required to confirm the level of interpretation they want to follow due to ambiguity.  This means that the final accountability is clearly with that decision maker, not any consultants involved in the project or authors of the Guidance document.

For example, guidance documents will consider normal equipment operating conditions for warehouse applications which is aligned to the principles of ATEX Zone 2.  However, the document may not align with regard to what ignition sources are considered present in normal operation under ATEX.

With AC motor technology common in forklift trucks, these may be perceived as non-sparking in normal operation and therefore acceptable for use.  However, whilst AC motors don’t have traditional sparking brushes, depending on their design they may still be defined as sparking devices in normal operation  by the formulae, which considers  the likelihood, that the rotor and body of the motor could come into contact during normal use.

In our experience, a number of forklift truck AC motors do not meet the non-sparking criterion as standard and require additional remedial action.  So, are standard AC motors on a specific fork truck non-sparking in normal operation?  Who makes the decision?

Similar interpretation may be required across the entire range of electrical and non-electrical components on a forklift truck as the Guidance document may not be explicit enough, but a decision has to be made what to address on the equipment.

So what would you do?

Whilst formal ATEX compliance may in some cases be considered unnecessary, it does provide explicit requirements for addressing all forklift truck ignition sources, and also puts the accountability clearly with the forklift truck OEM or conversion company supplying the protected forklift truck.

The alternative is to follow Guidance documents which may require you, the operator of the warehouse, to make or at least sign off the final decision interpreting the required level of action for motors, switches, sensors, brakes, lights, beacons etc. as it’s your ultimate responsibility to balance the risk.

Some operators therefore see the incremental cost to achieve ATEX compliance as fully justified taking all considerations into account.

If you are concerned about the storage of aerosols on your site, contact our technical team on +44 (0) 1273 456800 or