<div class="htmlview paragraph">This paper indicates why certain exhaust constituents from automotive vehicles are considered pollutants, describes the formation of these pollutants in automotive operation, and details techniques being used and considered to control these pollutants.</div> <div class="htmlview paragraph">The formation of pollutants-carbon monoxide, nitric oxide, hydrocarbons, particulates, and odor-in a variety of engine types and under a variety of conditions is described in detail. Vehicle emissions are also analyzed for real motor vehicle operation.</div>