There are no labs that test for drugs of abuse in air, all such labs test for the drugs of abuse metabolites in either urine, hair, blood or saliva. Why not test for such compounds in air? There are two main reasons why they do not: 1) the drug test is for "Metabolites" of the drugs that are produced by Liver enzymes--after the drugs are metabolized by your body. The ''air" does not produce any such drug metabolites; and 2) there is not a financial interest (or more appropriately there is no political pressure) for testing for drugs of abuse in air. After all, you cannot fire the "air" for testing positive for drugs of abuse. In fact, I believe that it is not possible to test positive for cannabis or meth if you inhale the 2nd hand smoke from such items.