We know that smoking tobacco cigarettes is associated with increased mortality, especially due to cardiovascular problems and cancers. Compare this situation to what we know (and don't know) about the dangers of marijuana smoke

What will be an ideal response?

Long-term marijuana smoking has been associated with impaired air flow in and out of the lungs, but we don't know if this is as bad as the link between cigarette smoking and chronic obstructive lung disease. No direct evidence links marijuana smoking with increased lung cancer. The smoke itself contains many dangerous components (tar, carbon monoxide, benzopyrene). Most cigarette smokers smoke several times per day, every day, whereas most marijuana smokers don't smoke as often. Marijuana cigarettes aren't filtered, and users tend to inhale deeply and hold the smoke longer.