An electronic air cleaner (10) includes a housing (20), a mechanical prefilter (30), an electrostatic precipitator cell (40) and at least one germicidal lamp (50). The electrostatic precipitator cell (40) includes a plurality of collector plates (42) for collecting thereon particulate material from the air stream. The germicidal lamp or lamps (50) are disposed to irradiating the collector plates (42) and any particulate material collected thereon with germicidal light to destroy microbial growth that might occur on the particulate material deposited on the collector plates. Reflectors (60) may be provided in operative association with the germicidal lamp or lamps (50) to concentrate the germicidal light unto the collecting surface of the collector plates (42).