Methods, apparatus, and systems for an airflow system, wherein the positive applied pressure is maintained at an approximately constant level over a variety of conditions. In one embodiment, a laminar flow is maintained by a foam housing and configuration. The use low air volume is enabled by using a closed system, wherein feedback information from the system is used to control the speed of an impeller. In one embodiment, moisture recirculation and recycling is applied to extract moisture from exhalation and inject the moisture back into the inhalation portion of the breathing cycle.