Even in modern F1 where mid-race refueling has been banned, pit crews are required by the FIA to wear safety equipment from head to toe during races. From helmets, safety goggles, fireproof suits and gloves, pit crews are just as geared up as the drivers during races because of safety reasons.
Unlike the drivers though, the pit crew are often only seen fully geared up during the race itself, as you'll see most of them not donning firesuits during practice sessions and qualifying. This is mostly due to the fact that cars are rarely serviced right on the pit box in these sessions, more often going in and out of the pit garages.