Engineering is concerned with the subjugation of Nature to man's needs'. Most of us now are horrified by this sentiment and think, as a matter of course, how Nature itself is affected by our activities and how to minimise them. The internal combustion engine is often held up as one of the chief curses of our times, mainly because of the emission of noxious gases, but also due to noise, personal injury and other more esoteric issues. It seems unlikely that the internal combustion engine will be legislated out of existence, but the quality of the engineering research required to meet the ever more stringent legislation, while delivering a competitive product is very high indeed. Places such as Athens, Mexico City and Los Angeles are badly affected, although other European cities have sometimes had to issue directives banning road traffice for extended periods due to smog exceedances.
Carbon monoxide is, of course, poisonous.
Under conditions of good engine design and control, exhaust after-treatment catalysts enable very low levels of emission into the environment to be achieved. Particulates are coming under very intense scrutiny in the late nineties. Current legislation limits the exhaust levels to a certain mass of particulate matter, but recent research indicates that it may be the number, rather than the mass of particles, which is related to health effects. If this proves to be the case, a great deal of work, some of it already underway at Cambridge, will be required to assess measurement methods and IC engine emission characteristics anew. New work is underway on sensors to measure particulates from IC engines.