Basic Emission Control Systems and What They Do

Automotive-generated pollutants come from three sources: tailpipe, crankcase blowby vapors and fuel vapors that evaporate from the fuel tank and carburetor.

Crankcase blowby vapors are eliminated as a source of pollution by recirculating the vapors into the engine for reburning through the Positive Crankcase Ventilation (PCV) system.