Abstract
The recent zoom of motor vehicle population especially in large cities in Japan throws serious problem for air pollution as with modern cities in other country.
Motor vehicle pollutants come from three sources- exhaust, crankcase emissions and evapolation. Except the last one depends mainly upon control of combustion and maintenance of engine.
Principal differences in burning mechanism of premixed and diffusion flames are described on standpoint of carbon or soot formation in order to undertsand the nature of exhaust from gasoline or Diesel vehicles incuding polybenzenoid substances some of which are considered to be a contributor for cancer.
Content of exhaust pollutants- carbon monoxide, nitrogen oxide, hydrocarbon and its incomplete combustion products alter in wide range according to driving conditions of vehicle as idling, acceleration, cruising and decceleration. It is important to note that hydrocarbon emission is extremely remarkable in decceleration step.
Diesel exhaust is rather clean compared to gasoline powered one and propane makes remarkable no improvement for exhaust pollutants.
Exhaust control devices- catalytic and afterburner- developed in America are briefly reviewed.
Improvement of engine itself in order to cut incomplete combustion to roll back air pollutants is also elucidated.
Estimations of American scholars for future hydrocarbon emission under exhaust control are cited.
