Can second hand smoke affect my drug test for employment ?

No, it cannot: The tests are designed to only pick up those people who are smoking pot directly and not inhaling it by secondhand smoke. Metabolites of the thc are detected in the urine at a cut off point of approximately 50 ng/ml. Secondhand smoke would not come near to giving you a level that high. This is intentionally built into the tests so as not to punish those people who are around others who smoke.