Nokia T21 user guide

Switch your device off in potentially explosive environments, such as near gasoline pumps. Sparks may cause an explosion or fire resulting in injury or death. Note restrictions in areas with fuel; chemical plants; or where blasting operations are in progress. Areas with a potentially explosive environment may not be clearly marked. These usually are areas where you are advised to switch your engine off, below deck on boats, chemical transfer or storage facilities, and where the air contains chemicals or particles. Check with the manufacturers of vehicles using liquefied petroleum gas (such as propane or butane) if this device can be safely used in their vicinity.