# Designing Safe General LED Lighting that Provides the UVB Benefits of Sunlight
## 5 Conclusions and Future Research  
This study proposes general indoor UVB LED lighting that produces vitamin D for the human body by reproducing solar UV characteristics. UV ray intensity was measured in summers (noon), and the characteristics of solar UVB were confirmed. To provide a safe level of UVB light, we measured and analyzed, based on distances and applied currents, the irradiance of two kinds of UVB LED light sources of 20 and 100 mW output specifications that could control the output of the applied current. To provide the UVB dose via indoor lighting, the application plan of each UVB LED light source was derived. We proposed general indoor UVB LED lighting with four 20 mW UVB LED light sources. The proposed lighting was controlled to have a brightness of 500 lux at a distance of 150 cm. EUVB irradiance of 0.00266 W/m\({}^{2}\) was provided by applying a current of 200 mA to the UVB LED light source. The proposed lighting was then measured using a spectral radiometer (CAS 140 CT) in a lighting box in which extraneous light was cut off. Additionally, a chemical hazard UV light item AUV and near-UV light NUV, which are the UV rays' hazard items of IEC 62471, were calculated. AUV and NUV were shown to be 0.001 and 0.002 W/m\({}^{2}\), respectively; thus, both were found to be in the safest grade, Exempt. Moreover, the EUV calculation value to find out the incidence of erythema by UV was 0.003245 W/m\({}^{2}\). If a person were exposed to the proposed lighting for 16 h, the EUV dose would be about 187.66 J/m\({}^{2}\), which would not cause erythema for general skin types (Skip Types 1-6). Furthermore, if the vitamin D calculation formula were applied as in the previous studies, a EUVB dose of about 187 J/m\({}^{2}\) would be provided to produce 374 IU of vitamin D, provided that an Asian (Skin Type 3) exposing 15% of their body were exposed to the proposed lighting for 16 h. This suggests that general indoor UVB LED lighting that can synthesize vitamin D in humans by providing safe UVB light using a UVB LED light source that can control the applied current should be developed.  
In the future, research will be required to build a lighting control system that works with UV smart devices to provide users with an optimal UVB dose via UVB LED general lighting and to offer UVB lighting services for individual users. In addition, it is necessary to validate the safety of the proposed system by conducting a clinical test for more varied skin types and by cooperating with the experts of photobiology and dermatology, and to commercialize the proposed technology to resolve health issues such as vitamin D deficiency.  
Investigation, methodology, and writing of the original draft: S.-T.O. Conceptualization and supervision: J.-H.L. Investigation: D.-H.P.  
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2017R1A2B2005601). The research was supported by the International Science and Business Belt Program through the Ministry of Science and ICT (2015-DD-RD-0068-04).  
The authors declare no conflict of interest.