Can a child fail a drug test by just being in the same room as people smoking it?

As far as I have been trained as a drug counselor, a person has a 4% chance of failing a drug test from a false positive. There are several medications that will also allow a drug test to be positive, including Advil and some antibiotics. All labs are required to save the urine or saliva swab for 30 days and a re-test can be requested. It is not possible for a false positive to come back wrong twice. The test will also show levels so if a person believes they have a false positive from being in the same room, the level should be very low.