At combustion of a working mix a number of the unhealthy person of products of combustion, in particular, окись carbon (WITH), various hydrocarbons (СН) and nitrogen oxides (NO) is formed. Though these substances also make only 1 % from the general exhaust (the rest is a nitrogen, dioxide of carbon and water steam), they are very harmful and neutralisation demand. There are some ways of struggle against harmful exhausts – for example, mix pauperisation on which the engine or рециркуляция an exhaust works – but any of them will not be compared by efficiency with catalytic neutralizer.