
DM Under The Bridge |

Sorry, but High Fantasy for me doesn't mean getting black lung because of passing through a mine, getting rabies because you fought with wolves or getting an STD because one of the PCs went to the brothel. That isn't high fantasy. Just like inconveniencing PCs with carbon monoxide or other poisonous gas.
If your fantasy world has diseases (like Pathfinder) then STDs are possible.

Shadowborn |
2 people marked this as a favorite. |

Forgive me if someone has already mentioned it and I missed it because of all the posts of people accusing other people of badwrongfun, but the idea of bad air as a hazard is already in the game. So whether you think it's a good idea or not, rules have been established to accommodate the idea.
Bad Air (CR 1 or 4)
An invisible hazard, pockets of low-oxygen gas present a danger to miners and spelunkers as well as cavern-delving adventurers. Nonflammable gases such as carbon dioxide or nitrogen are CR 1 and require a DC 25 Survival check to notice. Creatures breathing the air must make a Fortitude save (DC 15 + 1 per previous check) each hour or become fatigued. After a creature becomes fatigued, slow suffocation sets in (Pathfinder RPG Core Rulebook 445). Creatures holding their breath can avoid these effects.
Flammable vapors such as coal gas are much more dangerous (CR 4). The gases displace breathable air in the lungs, causing fatigue as described above. In addition, any open flame or spark causes an explosion for 6d6 points of damage (Reflex save DC 15 for half) to all in the cavern or within 5 feet of an entrance. The fire burns away the oxygen in the air, leaving it unbreathable for 2d4 minutes. After an explosion, flammable gas usually takes several days to build up to dangerous levels again.