Odors emitted from municipal wastewater treatment plants belong to a group of pollutants, which is the main cause of people complaining about atmospheric air quality. The limitation of emissions of unpleasant odors generated by wastewater treatment plants by using appropriate deodorization methods is omitted on numerous occasions. This can have a negative influence on public trust and the quality of atmospheric air. The article presents basic information on the characteristics of odors from wastewater treatment lines and wastewater processing and management lines in a model biological wastewater treatment plant conducting the biogas recovery process and also information is provided on deodorization methods, such as odor masking, biofiltration, thermal disposal and diffusion through activated sludge dedicated to neutralization of odors in biological treatment plants. The main focus is on the field olfactometry technique, which is one of the tools used in environmental protection. Its application facilitates performance of tests concerning the assessment of olfactory properties of odorants in polluted air.