An electrophotographic copying apparatus which includes a rotatable photoreceptor member having a photoconductive surface for repeated formation of an electrostatic latent image of an original thereon. A casing is disposed around the photoreceptor member and included a corona charger for uniformly charging the surface. An exposure device is provided for exposing the charged surface to image light of the original through an optical assembly including an illuminating light source so as to form the electrostatic latent image of the original thereon. A system is provided for eliminating harmful gases generated by the corona charger disposed within the copying apparatus.