TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred System: A first energy maximum is produced by a first emitting region in a first wavelength band (lambda1) (160-200) nm of ozone-producing radiation and a second energy maximum is produced by a second emitting region in a second wavelength band (lambda2) (230-280) nm of germicidal radiation. The generator also comprises a third emitting region of antimicrobial radiation which generates a third wavelength band (330-360) nm. The generator emits UV radiation to generate free oxygen radicals, which react with the pollutant. The system comprises at least two (preferably many) radiation chambers and at least one radiation source (preferably many) to irradiate the chambers with distinct spectra of UV radiation. The first and the second chamber are optically isolated by an opaque isolator, which prevents exposure of one chamber to radiation emitted in the other chamber. The isolator is constructed of aluminum and comprises a base coated with a material selected from silver, silver oxide, copper, copper oxide, microcrystalline titanium and titanium dioxide. The radiation source is a UV lamp. The system further comprises a power controller; a timer associated with the power controller; a heater mounted within the housing for heating an external environment; a cooler mounted within the housing for cooling the environment; and a filter mounted within the housing for filtering the air. The power controller comprises a source of AC power, a pollution detector and switch for selectively activating the radiation source in response to a pollutant indicator signal from the detector. The timer determines a selected time in which power is supplied to at least one radiation source. The pollutant detector is capable of detecting the presence of CO, CO2, C6H6, CH4, HCHO, SO2, O2, H2, H2S, NOx, O3 and aerosols. The housing inserts a return duct of a heating/ventilation/air conditioning (HVAC) unit. EXAMPLE - An air purifier having a voltage of 120 volt AC and a lamp configuration of 0.25 inches was placed inside a test chamber and operated for 24 hours. The power consumption of the air purifier was maintained at 108 V, ultraviolet intensity was maintained at 14200 microW/cm2 and the radiation level was maintained at 0.5 mR/hour. The concentration (parts per million (ppm)) of carbon monoxide gas was taken after 4, 8, 12 and 24 hours and was found to be 35, 30, 0.7 and 0.7 respectively. It was observed that the air purifier reduced the level of the CO well below the OSHA limit (50 ppm) at some time before the four hour reading and was maintained at the 4 hour level or further reduced after 8, 12 and 24 hours.