Abstract: A system of geometric guides and baffles is used for directing and diffusing external air drawn from a fan blower before distributing the flow evenly to the outlet of a fan filter unit. This arrangement not only reduces the turbulence within a fan filter unit but also maintains the particle count of air drawn through the same system. Furthermore, the present invention is implemented in dimensions substantially similar to that of the fan blower. As such, the present invention minimizes noise of a fan filter unit even in confined clean room facility.