A commenter asked a great question on one of our older posts. That question was, does second hand smoke affect the result of a drug test? It wouldn’t be fair if it did, of course. As the commenter points out, (medical) marijuana is legal in some states, and if you are not smoking it, you should not be punished for having been around second hand smoke.
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. Here is what the test manufacturer said on the subject:
“It [second hand marijuana smoke] would not register on our tests. We had a test where someone was placed in a isolated room with THC smoke was being pumped in for 24 hours straight and the person did not register. On a lab test it did pick up about 3 or 4 nanograms but as you know instant tests are set at 50ng/ml.”
Even at the confirmatory GC/MS lab urine drug test level of 15 ng/ml, you would still not test positive for marijuana due to second hand smoke. The cutoff level for the saliva drug test is 100 ng/ml (so again, second hand smoke would not produce a positive).
When it comes to hair, the manner in which the lab analyzes your sample makes external contamination impossible. Hair drug testing labs only detect the metabolite of marijuana, THC-COOH. This is only produced when marijuana directly enters the body (and not through someone’s second hand smoke, which is indirect) and is broken down by the body. The hair test will not pick up contaminants from the outside.
So, even if you have been exposed to second hand smoke, if you have not yourself smoked you should be safe with our tests. Thank you to our readers for such great questions and I look forward to more in the future!