Survey of Nationwide Automotive Exhaust Emissions and PCV System Conditions -Summer 1970

Results of a nationwide vehicle exhaust emission survey and PCV system check are presented. More than 75,000 vehicles were tested in 15 metropolitan areas. Hydrocarbon and carbon monoxide emissions are summarized at idle and 2500 rpm (free running), and the condition of the PCV system is correlated with vehicle age.

Vehicle distribution curves for hydrocarbon and carbon monoxide emissions are shown for selected year groupings of American and foreign-built vehicles. The effect of carburetor adjustment (air-fuel ratio, rpm) on idle emissions is demonstrated for those 32% of the total vehicles for which adjustments were made.