A painting system includes a paint spray booth ventilated by process air including a combination of outside make-up air and a portion of the exiting process air which is returned to the booth, the returned air being the main component of the combination. The humidity of the air in the paint spray booth is controlled by routing a first minor portion of the process air, exiting the booth, through a desiccant dehumidifier, which removes moisture and volatile organic compounds (VOCs) from this process air portion before it is sent back to the paint spray booth. The dehumidifier is designed so that at any given time the process air portion contacts only part of the desiccant bed while air heated to approximately 250 F. in a paint cure oven is exhausted from the oven and directed through the remaining part of the desiccant bed in order to dry, and thus regenerate, the desiccant for continued use. The dehumidifier is designed so that a continual exchange of dried desiccant for moisture laden desiccant respectively takes place relative to the process and heated air streams. The heated air also removes a large portion of the volatile organic compounds removed from the first minor portion of the process air. A second minor portion of the process air exiting from the paint spray booth, equal to the volume of make-up air, and the heated regenerative air exiting the dehumidifier are routed through a control device, such as a thermal oxidizer, which destroys the volatile organic compounds contained in this air before exhausting it to the atmosphere.
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