HCN Effects on Humans:
Hydrogen Cyanide can cause rapid death due to metabolic asphyxiation. Death can occur within seconds or minutes of the inhalation of high concentrations.
3,404 ppm Death after 1 minute exposure
270 ppm Death after 6-8 minute exposure
181 ppm Death after 10-minute exposure
135 ppm Death after 30-minute exposure
10 ppm OSHA permissible exposure limit (PEL)
4.7 ppm NIOSH recommended exposure limit (REL)
ppm=parts per million Recent study estimations (Hathaway et al. 1991)
5.6% HCN lower flammable limits in air (percent by volume) 40.0% upper flammable limits in air (percent by volume)