Can you test positive for marijuana if someone blew it at you?

If you are not an avid pot smoker and they wern't blowing massive amounts in your face for countless hours the answer would mainly be NO.

THC metabolizes fairly quickly and can only be detected for a few days if you are a once in a great while smoker, as compared to weeks for a habitual smoker.

Urine tests would not detect enough traces of THC to come up positive if you are not a smoker and were simply in the vicinity of the smoker. HOWEVER, skin or hair tests MIGHT come up positive if the people smoking around you were doing so in very LARGE quantities for a long period of time.