Abstract: A shelter system for use within an environment having air includes an enclosure disposable within the environment formed of an air impermeable material. The enclosure is expansible from a collapsed configuration to a usage configuration and is configured to define an interior chamber, to contain a quantity of air within the chamber, and to substantially prevent entry of the environment air into the chamber. An oxygen generator disposable within the enclosure includes a housing and a quantity of oxygen-producing material disposable within the housing for generating oxygen by spontaneous chemical reaction, the oxygen being discharged to the enclosure chamber. A carbon dioxide removal device disposable within the enclosure includes a chamber, a reactive material disposed within the chamber for removing carbon dioxide from the enclosure air, and a fan initiating flow through the chamber. The system may be used within a building, a vehicle, or an open environment.