A relatively new source of air contamination, automobile emissions posed different problems than manufacturing discharges such as coal smoke. Before the Industrial Revolution, levels of toxic chemicals in the air were relatively low, but increased fossil-fuel production and use dramatically decreased air quality. The addition of many thousands of cars on the road in the years after World War II intensified the spread of air pollution, added more and newer sources of pollutants, and most immediately threatened many major cities.
As early as 1959, eye irritation was reported in Los Angeles County on 187 days; in 1962, 212 days. A typical car produced in 1963 (without pollution control devices) discharged 520 pounds of hydrocarbons, 1,700 pounds of carbon monoxide, and 90 pounds of nitrogen oxide for every 10,000 miles traveled. In 1966, 86 million of approximately 146 million tons of pollutants discharged into the air in the United States was attributable to motor vehicle traffic.
As early as 1953, Los Angeles County Supervisor Kenneth Hahn inquired of Detroit automobile makers as to whether research was being conducted to eliminate emissions. The response was vague. With the threat of mandatory federal regulations, the auto industry began to install crankcase blowby devices (which returned unburned gases to the combustion chambers) on their cars. This was a significant advance because crankcase blowby produced 25 percent of the engine's hydrocarbon emissions. This equipment became mandatory on all cars sold in California beginning with the 1963 models.
Catalytic converters were required on all 1975 cars sold in California. Leaded gasoline, however, played havoc with the catalysts. One solution was to use lead-free or unleaded gasoline. (Another was the unauthorized removal of the devices by motorists.) While non-leaded gas became available, the complete phase-out of leaded gasoline, as stated earlier, did not commence until 1986.
