Good afternoon: Colman lantern? sheesh it will tell you when the oxygen is insufficient to stay alive by dimming or going out. If it goes out, how will you find your way back to safer areas? Then again there are areas of explosive gas of different types. An open flame like a colman latern is asking for it. This is why the Davies lamp was invented. Soo, always keep a backup flashlight with you.
Best advice is if you don't have proper equipment, training, stay out of them. I am still alive though sheer luck.
Don Jose de La Mancha