Abstract: The invention is a system for detecting air conditions in a residential room, apartment, or other building that suggest the manufacture of illicit drugs or other illegal substances, such as methamphetamine. The invention includes a compact sensor that may be secretly installed in a room to sense levels of VOC's and/or other solvents and/or other hazardous chemicals in the ambient air of the room that are indicative of illegal drug or chemical manufacture. Upon sensing an event at or above the pre-determined alarm level, the sensor system signals an alarm, preferably a wireless, hard-wired, or other electric or electronic signal to a remote location, such as a building manager's office, a police station, or other community authority.