Abstract: A moisture resistant air filter has a generally planar air permeable filter media with an upstream and downstream surface and a peripheral edge. A frame surrounds the filter media peripheral edge providing an inner peripheral frame surface to which the filter media peripheral edge is attached. The upstream and downstream panels are integrally formed with the frame, the upstream and downstream panels having large openings therethrough. The frame and the panels are formed of paper board of about 0.016 to 0.060 caliper and coated with polyethylene or polypropylene.