Presented herein are various techniques for cooling a UV light source and keeping it within a predetermined temperature range. One embodiment is directed to using Venturi pump for the thermal control. Another embodiment employs a mechanical or electrical self-adjusting valve. Another embodiment is directed to using a forced air system to actively blow air across the light source. Examples of the device are an air cleaner, a vacuum cleaner, a mobile floor-sanitizer, and a hand-held sanitizer.