Carbon monoxide

TL1 (from incomplete charcoal combustion); LC4.

Carbon monoxide is an inhaled poison that acts by bonding to hemoglobin, blocking oxygen transport in the blood. Initial symptoms are headache, drowsiness, and mild confusion. This is a an area-effect respiratory agent. Roll vs. IQ- 2 to realize something is wrong. Once carbon monoxide reaches lethal levels, there is a 10-second delay and an HT roll to resist. If the target fails the HT roll, he is Drowsy (p. B428) with a -2 to DX, and IQ and begins to suffocate (p. B436). If the target succeeds, he is still in life-threatening danger until he finds fresh air. Cannot be detected by smell. Not normally purchased; can be produced by incomplete combustion of charcoal (TL1).

Source: GURPS 4th - Mysteries, page 36