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Exposure of the human skin to sunlight is essential for Vitamin D production. Due to our modern indoor lifestyle an increasing part of the population shows insufficient Vitamin D levels, especially in wintertime. Exposure to artificial UVB radiation can help in maintaining a sufficient Vitamin D level. The provided dose should be high enough to be effective, but low enough not to cause damage to skin or eyes. We designed a UVB module for integration in office luminaires that provides a very low UVB irradiance level that leads to an effective dose in a full working day. Ideally, the intensity distribution for a ceiling-mounted UVB module provides a uniform irradiance level on the face and hands of a sitting person. The final design is a balance between UVB LED availability, optical material use, manufacturing considerations, and required light distribution.