Second hand marijuana smoke and Drug Testing for THC

Dear Ask The Doctor: I dont do drugs, my boyfriend smokes marijuana and im always in another room but i can smell it, we have unprotected sex alot and i give monthly ua's will i test positive for thc?

Dear Dana: The good news is that none of our home drug test kits (hair, urine, or saliva) will pick up exposure to second hand marijuana smoke as a positive result. The lungs do not filter THC out of smoke; they absorb it in small amounts. Smoke inhaled secondarily must infiltrate the lungs in heavy concentrations in order to produce clinically positive tests. Smoke exhaled by one person and inhaled by another or smoke that floats in a space may not contain the original high concentrations of THC; hence a small-to-zero likelihood that drug tests could read positive. Also, most immunoassay drug tests, including standard EMIT, ELISA and RIA tests, are set at high thresholds intentionally to avoid false-positive results due to incidental ingestions of second-hand smoke. So, unless a urine sample is taken right at the time a large amount of THC is inhaled, a drug test should remain negative.