The worth of a fire detector is determined as much by its ability not to respond to stimuli that are generated from non-threatening sources as to respond in a timely manner to an actual fire. Photo-electric and ionization smoke detectors react to a greater or lesser degree to all particles that enter the sensing chamber, and, by themselves, the detectors can not distinguish smoke from a nuisance aerosol. The fire-emulator/detector-evaluator (FE/DE) is used to produce smoke and nuisance aerosols representative of what could be present immediately adjacent to an installed detector, and provides a test bed to determine the response of spot-type detectors to physical products (temperature, gases, and smoke) formed in simulated fires, as well as the response to stimuli not associated with a fire threat. The analog output of a multi-sensor detector is measured as a function of aerosol type (peanut oil and clay dust), concentration, and air flow, and is compared to the response of the detector to a flaming fire, and to the extinction of laser light in the FE/DE test section at optical densities up to 0.12 m-1 .