Thankfully there are many places aboard a carrier where gas, munitions, and other flammables are not! In fact in all navies there was very much an effort made to mark the line between crew living space and work space.

It was not always perfect, or large. But it was there in most cases. And in addition to distinguish between shops and work spaces that were dangerous and those like a Squadron Ready Room, Comms Shop, or Supply office, which were much less so.

While standard safe practices also were incorporated. It varied from nation to nation, but the majority of planes aboard wouldnt be kept fueled and armed at all times. They would be parked either on the Hangar or Flight decks, and while still a fire risk, were much less of one. Before they needed to be in action, the crew would then spend the sometimes several hours, fueling, warming up, and arming the aircraft. The munitions would be brought up through armored elevators and either mounted right away, or potentially stored for as short a time as possible before mounting, while portable hoses allowed for fueling.

So you can see in normal conditions there was an appreciation of the fire risk. But if caught in a situation where aircraft were in the middle of this process, things can get dangerous real fast. Even before the quality of damage control equipment or practices gets into the picture. This is in essence what befell 3 of the 4 IJN carriers lost at Midway.

In the USN then it was generally up to the Captain of each vessel to at his discretion, establish designated Smoke Pits and still is today, though often it was simply a recognition of areas the crew already liked to gather communally. On a carrier there are a few ones that are prime real estate. The gantry walks outside the hangar on either side are out of the way, have fresh air, and of course, provide a view, but at night of course are a risk for being spotted by the light. Similar as well are the forecastle or fantail, open spaces where the men might congregate for a smoke. I have seen references to men smoking inside in work spaces once or twice, so really just seems to be a ship to ship thing. But in the USN in the Pacific, men liked to spend lots of time out in the fresh air for comfort to begin with.

Officers though had it a bit nicer, while designs would change with the war. Before the US entry into war YORKTOWN even had a Cigar locker in its Wardroom Pantry for the use of her officers. Rank certainly had a few perks in that department.