An air intake system for an internal combustion engine

A fugitive hydrocarbon treatment module 14 and system for controlling the emission of hydrocarbons from the air intake system of an engine 20 are disclosed. The treatment module 14 includes a zeolite adsorber unit 22 positioned in the air intake system such that all gases flowing to and from the engine 20 through the air intake system pass through the adsorber 22.. This allows hydrocarbons borne by any back flowing gases to be adsorbed upon the substrate of the adsorber unit 22 when the engine 20 is shut down and desorbed from the adsorber unit 22 when the engine 20 is in operation.