Apple watch vs Ex

Manual says:
“Explosive atmospheres  Charging or using Apple Watch in any area with a potentially explosive atmosphere, such as in areas where the air contains high levels of flammable chemicals, vapors, or particles (such as grain, dust, or metal powders), may be hazardous. Obey all signs and instructions.”
Link: https://help.apple.com/watch/#/apdcf2ff54e9

Question: charging is hazardous or the area? Shall the watch be Ex certified? Does it say anything about not bringing the device into an Ex Zone?
Answers are definite.
Any comments welcome…
Keep up good work.