The firefighters should better not wear the contact lenses which may be too close to the fire resource. It is so dangerous for the contact lenses to meet the fire in the close distance which wil be melt at the small time if the temperature is high enough. Thus, firefighters should better not wear the contact lenses. Instead, it is safe for them to wear the eyeglasses.
No, it is forbidden.
People work with sparks or fire can't wear contact lenses including firefighter, welding worker and cook, because the fire or spark may burn the contact lenses and hurt the cornea when they are working. These workers are only allowed to wear contact lenses when they wear goggles at the same time.
Of course not. Although there is no specific limitation of temperature. It has rules that firefighters can not wear contact lenses, otherwise the contact lenses may melt in their eyes. As we know, when you buy a pair of contact lenses, the seller may tell dos and don'ts. Certainly, he will tell you pay attention to temperature extremes such as fireplace.