The subject invention provides devices and methods for regulating the composition and pressure of one or more gaseous species and/or volatile chemicals present in a volume enclosed by a flexible, semi-rigid, or rigid packaging material. In one aspect, the subject invention provides a device designed to be inserted into an enclosed volume, the device comprising a predetermined concentration of one or more gaseous species and/or volatile chemicals contained in a capsule comprising packaging materials selected according to the desired composition, pressure or concentration, and rate of permeation of the content of the device. In another aspect, the subject invention provides a method for regulating the atmospheric condition within an enclosed volume, the method comprising inserting the device provided herein into the enclosed volume and allowing the content of the device to permeate into the enclosed volume over a desired period of time.
