Bad Air CR 1 or 4
XP 400 or 1,200
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. 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.
Section 15: Copyright Notice
Pathfinder RPG GameMastery Guide, © 2010, Paizo Publishing, LLC; Authors: Cam Banks, Wolfgang Baur, Jason Bulmahn, Jim Butler, Eric Cagle, Graeme Davis, Adam Daigle, Joshua J. Frost, James Jacobs, Kenneth Hite, Steven Kenson, Robin Laws, Tito Leati, Rob McCreary, Hal Maclean, Colin McComb, Jason Nelson, David Noonan, Richard Pett, Rich Redman, Sean K Reynolds, F. Wesley Schneider, Amber Scott, Doug Seacat, Mike Selinker, Lisa Stevens, James L. Sutter, Russ Taylor, Penny Williams, Skip Williams, Teeuwynn Woodruff.