Abstract: A robust, relatively simple air quality control system that can control the air quality in buildings during both the heating and cooling seasons. In one illustrative embodiment, a first air stream is directed through an air treatment module and back into the inside space. A desiccant in the air treatment module adsorbs water, volatile organic compounds and/or particulate material from the first air stream. A second air stream is then directed through the air treatment module to a location outside of the inside space. The second air stream is preferably heated relative to the first air stream so that at least a portion of the adsorbed water, volatile organic compounds and/or particulate material are desorbed from the desiccant into the second air stream. The second air stream carries the desorbed water, volatile organic compounds and/or particulate material to a location outside the inside space.