Development of a Safe UVB LED Indoor General Lighting to Support Vitamin D Synthesis in the Human Body

It is essential to be exposed to the ultraviolet B-rays (UVB) of the sunlight for the synthesis of vitamin D to maintain sound human health. However, in recent years, modern people have been foregoing sunlight exposure as they stay longer indoors and since it has been found that erythema and skin cancer may be caused by excessive exposure to ultraviolet rays. This raises the issue on health deterioration, such as vitamin D deficiency caused by lack of UVB exposure. Recently, artificial lighting has been developed to provide UVB exposure indoors and several research cases have been introduced to confirm the safety of UV lighting. However, research to develop UVB lighting that meets safety standards, along with substantiating studies on whether vitamin D synthesis is supported, is lacking. In this paper, a UVB LED indoor lighting that supports vitamin D synthesis through indoor lighting environment is proposed and the effects of vitamin D synthesis on the proposed lighting through animal experiments are confirmed. The light characteristics of the 100mW UVB-LED light source by input current were measured and analyzed. The input current satisfying the risk criteria for the ultraviolet region of IEC 62471 was derived, and then it was applied to the proposed lighting which realized the safest grade “exempt” for the IEC 62471 UV hazards. Animal experiments were also performed to confirm the effects of the proposed lighting on the body's vitamin D synthesis. The results confirmed that the vitamin D blood content in the rat group, raised in the proposed lighting environment, was significantly increased.