An air purifier (10) for an animal transport vehicle, such as a horse float (12), has a first air flow passageway (22) for receiving air and directing it in a first direction, and a second air flow passageway (40) continuous with the first air flow passageway and adapted to direct air received from the first air flow passageway in a second direction substantially opposite to the first direction. There is a bend region (42) joining the first and second air flow passageways where the change in the direction of air occurs. An air egress passageway (34) has an opening (36) adjacent the bend region so as to divert some of the air therethrough. The passageway (34) is so configured as to create a venturi effect on the diverted air. A filter (43) is located downstream of the second air flow passageway (40) and is mounted across an opening of the transport vehicle so that air flowing through the second air flow passageway is filtered before entering the transport vehicle.