Journal of the .4uwrican Medical ~4ssociatiotz (I923, 3z, 385)
under the title " Health Hazards from Automobile Exhaust Gases in City Streets, Garages and Repair Shops." In the open country, with the limited number of operating autos, pollution is not likely to be serious, but in narrow, congested city streets, and in overcrowded garages, the concentration of the products of imperfect combustion of the motor liquids is apt to be marked. Most autos discharge their exhausts horizontally about the level of the car axles, so that the air on the level of the occupants of the following car is sure to be polluted. The investigators made many tests and found that this method of discharge is decidedly objectionable. They recommend a vertical exhaust by means of a pipe directed so as to cause the exhaust to be mixed with air above the respiratory zone of the passengers. Such a modification in auto construction will, probably, not be brought about except by legislation. Henderson and Haggard suggest that the simplest and most efficient method would be taxation. If a license fee of say $25, in addition to the regular fee, was levied on all cars not provided with vertical exhaust, the condition would be promptly remedied.
The amount of visible smoke is not an index of the carbon monoxide content of the gases discharged. Chemical tests showed that the air of garages and repair shops is, as a rule. quite insanitary. Man), mechanics and drivers suffer frequently from headache and other objectionable conditions due to partial asphyxiation. Fatal accidents in garages are frequently reported. The ordinary horizontal exhaust mixes poisonous gases in the air of city streets to a depth of about ten feet. It dissipates the heat of the gas and prevents it rising and passing away. The vertical exhaust is far better.
H.L.