The present report on 'Investigations on the Physiological and Psychological Effect of Automobile Exhaust Gases on the Population' is a partial study for a research project assigned by the Association of German Engineers, operating under instructions of the Federal Traffic Ministry, under the heading: 'Investigations on Environmental Pollution and Damage Due to Vehicular Traffic in Urban Areas (Noise and Exhaust Gases)'. The objective of this report is to evaluate presently available information in order to: Determine the relationships between exhaust gas pollution from motor vehicles and the resulting damage to the health of, as well as the stress on, the population in urban areas, and ascertain the possible empirically based parameters of the human capacity for environmental stress. Inorganic and organic pollutants are considered for effects ranging from irritation to acute toxicity.