An adaptor includes a housing and a plurality of blades disposed inside the housing. The adaptor can be utilized with a breathing assist device such as a Continuous Positive Airway Pressure (CPAP) machine. Air flowing through an air flow path defined by the two ends of the housing is delivered for use. The blades within the housing are aligned in a direction parallel to the air flow path. The blades within the housing can be parallel, zigzag or chevron shape and are designed to facilitate condensation of water from the air flowing over the blades. The adaptor will reduce rain-out effect in the breathing device.