distribution of air flow around the area of the air cleaning or filtering media mounted in the inlet i e most uniform velocity distribution in the duct the blower unit 22 is shown in fig1 through 3 mounted at a 45 u00b0 angle with the horizontal of the enclosure an angle which produces excellent results the enclosure or duct 24 has its inlet opening 25 through its rear portion 26 which is at the left in fig1 a filtering or air purification unit 28 is mounted inside the enclosure to cover the inlet opening the sides of the enclosure are provided by sidewalls 30 and 31 and have no openings therein the top 32 and bottom 33 of the enclosure also have no openings therein the blower unit 22 is mounted on the front wall 34 of the enclosure the basic elements of the blower unit which may be a standard commercially available unit are its housing 36 a blower wheel 38 inside the housing and a motor 40 mounted on one side of the blower housing and operatively connected to the blower wheel 38 other variations of this basic configuration exist including single motor and dual blower units however the basic concept defined herein remains constant the rotor 38 when turned by the motor 40 draws air in at each end through openings 42.