Hi Amy

HSE UK : Hazardous Area Classification and Control of Ignition Sources

ATEX Safety | Potential Sources of Ignition

ATEX Safety | Hazardous Area Classification

ATEX Safety | Static Ignition & Thermal Instability

The above three links are all part of a series on this topic

under the definition of an ignition source in the Haz Sub regs the simple answer would be yes:

ignition source—
(a)
means any agency or agent (including any item, product, part of a facility structure, or piece of equipment) capable of igniting a flammable gas, vapour, or other form of combustible substance; and
(b)
includes a fire, flame, or spark, or anything capable of producing a fire, flame, or spark — Health and Safety at Work (Hazardous Substances) Regulations 2017

However with your reference to Zone 2 I would assume that you are controlling the risk of ignition through compliance with AS/NZS (or IEC/EN) 60079.14:2009 which makes the question more about the ignition energy required / energy available, rather than specifically how that energy has been created/stored/discharged, and therefore would need someone to look at your unique situation to give you a more definitive answer.

If there is a risk of potential explosion or ignition sources, then yes you should ban them. All petroleum plants will not allow phones on site due to the risk. Paint plants have areas where static would cause explosion. The reason service stations 'ban' mobile phone use on forecourts is that, static from clothing can cause fumes to ignite - you don't need a mobile phone for that to happen but using one can create the necessary electrical charge to ignite any fumes. I have witnessed this on a forecourt and, believe me, you don't want to be anywhere near when it happens.

@Dianne Campton I had been using the example of mobile phones on forecourts in a discussion with our staff around HazSub, when a worker pointed me to Z's website that states they had conducted an independent risk assessment and the "findings showed mobile phones as an ignition source poses no risk to our customers" while refueling. The same worker reminded me that at several stations you can use your phone to pay also. Z's reasoning is that mobile phones now have batteries that are more efficient and fully enclosed, and phones are manufactured to be dust and water resistant. Makes for an interesting read.

We all have iphones, however purchase Lifeproof AP65 rated covers to ensure they are safe in our hazardous atmosphere zones, can also buy these covers for ipads/tablets if needing to do inspections etc.
Unsure on clothing however as these areas a afire risk we ensure the staff are wearing 100% cotton overalls. Our electrician wear electrical arc rated overalls which may suit your needs as well.

means any agency or agent (including any item, product, part of a facility structure, or piece of equipment) capable of igniting a flammable gas, vapour, or other form of combustible substance; and — Health and Safety at Work (Hazardous Substances) Regulations 2017

Worthwhile remembering that fine dust (of any kind) combined with an ignition source can result in an explosion,typically something disturbs a dust buildup which suspends it in the air and then whammo when an ignition source does it's thing - has happened in NZ before (Plastic moulding company and a Flour mill). Some Dust Explosion Info here

On a different note. It's interesting how we are now been asked to scan for Covid 19 at the petrol pump on a forecourt when a few years ago this was a no mobile phones allowed area.

They also have pay at the pump using cell phones, so it must be unsafe until we need to get money.....

Attached is surveillance camera footage of an incident at a petrol station that I use in training to demonstrate the hazards of static electricity. I draw people's attention to the fact that the person in video returned to their seat in their car after they started refuelling, and made themselves comfortable. They got out when the bowser stopped and adjusted their clothing before they went to take the bowser from their car. A static discharge ignited fuel vapours.
The act of 'making themselves comfortable" caused generation of static within their clothing. The nature of their clothing adjustments promoted movement of the charge into their arms, increasing the static potential.
How does this relate to use of cell phones on a petrol forecourt? The average person wants to make themselves more comfortable when they fiddle with their phones, so they tend to go and sit in their car, the move about to make themselves comfortable...
Asking people to not use cell phones on the forecourt is now more associated with attempting a form of behaviour modification to prevent another activity - returning to the vehicle.

I believe the video is sufficient an answer to the question about static electricity and its hazards.