Question

What change to cars took place in the 1970s after the Clean Air Act reduced the allowable levels of exhaust emissions? How did that change affect the levels of gaseous emissions from cars?

Answer 1

In 1970, when the Clean Air Act was passed, a regulation was adopted that requires the design of gasoline nozzles that capture evaporative emissions during fuel supply in cars.

The controls on emissions have successfully reduced the emissions produced by automobiles in terms of the amount of pollutants per distance traveled. However, the substantial increase in the distances covered by each vehicle, as well as the increase in the number of vehicles in circulation, has the consequence that the total decrease in emissions is decreasing.