Is second hand marijuana smoke harmful to children?

Answer:

yes. marijuana has far less harmful chemicals but up to 5 times as much tar as tobacco.

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Marijuana has recently (June, 2009) been added to the Proposition 65 list of chemicals known to the state of Calfornia to cause cancer. Second-hand marijuana smoke contains 50% to 70% more harmful chemicals than tobacco smoke. See http://oehha.ca.gov/Prop65/docs_state/mjcrnr061909.html

Children can be affected differently than adults. While large doses of THC act as a CNS depressant, lower levels of THC can act as a stimulant, so kids can go around talking incessantly when exposed to a parent's smoke. Teenagers' mood swings can get worse, and some kids become forgetful, angry, or violent after having been in a smoke-filled party room.