Two respiratory inhalers and selected over-the-counter products were given to human subjects before testing their breath with the S-L2. Nine common volatile substances (acetaldehyde, acetone, ether, ethylene glycol, isopropanol, methanol, methylene chloride, toluene, and trichloroethylene) were sampled using the S-L2 and simulated breath samples. Resulting S-L2 ready, pass, warn, and fail lights and corresponding digital readings were recorded for each test. The only significant readings were those produced by toxic or lethal levels for acetaldehyde, ether, isopropanol, and methanol. The author concludes that the Alcolmeter S-L2 has sufficient specificity for police officers to rely on its readings when investigating impaired drivers. 5 references and 1 table