arpadveress 
Employers must provide workers who work in Ex zoned areas with appropriate clothing that does not create the risk of an electrostatic discharge igniting the explosive atmosphere, eg anti-static footwear.
The clothing provided depends on the level of risk identified in the risk assessment. Pls check your EPD.
Have you ever checked what your PPE policy saying?
What about cleaning? Is it a procedure of yours with validation?
If not at all, you may have an unwanted ignition source around, but many at the same time.
Keep up good work!
