An apparatus for aerosolized powder delivery includes first and second chambers containing gas at first and second pressures, respectively, above atmospheric pressure. A powder is contained within the first or second chamber. The first chamber has a first external wall and a separating wall shared with the second chamber. The first external wall or the separating wall is configured to rupture if the pressure difference across it becomes equal to or greater than a threshold pressure difference. Specifically, the apparatus is configured so that the difference between the second pressure and atmospheric pressure is greater than the threshold pressure difference. Initially, the difference between the second and first pressures is less than the pressure difference required to rupture the separating wall, and the difference between the first pressure and atmospheric pressure is less than the pressure difference required to rupture the first external wall.