Hydrogen Cyanide in Cigarette Smoke

I'm smoking what? Cigarette smoke contains some pretty dangerous chemicals, one of which is hydrogen cyanide. Found in mainstream and sidestream smoke, it is extremely toxic.
It was used in World War II as a genocidal agent, and reports have indicated it may have been used along with other chemical agents against the people of the Kurdish city of Halabja in northern Iraq during the Iran-Iraq War in the 1980s.