How dangerous is weed?

"Marijuana is the safest therapeutically active substance known to man... safer than many foods we commonly consume." DEA Judge Francis L. Young, Sept. 6, 1988

The most dangerous aspect of cannabis in health terms is how one chooses to use it. Smoking anything is harmful to a degree, but weed is nowhere near as dangerous as commercial cigarettes in that respect. This is why we have alternate methods of cannabis use, such as vaporization and edible consumption.

It would be dangerous if one were to consume too much and fall asleep on the job, but this is as much a danger (or less) as taking cough medication or not getting enough sleep the previous night.