## 2 Materials and Results  
Some publicly available databases of LED spectral power distributions (SPDs) are used to provide a representative dataset of commercially available LED products. The following databases were used: the \"Real Light Source SPDs and Color Data for Use in Research\" database [38] provided by the Pacific Northwest National Laboratory (PNNL), USA, and the \"EMPIR 15 SIB07 PhotoLED\" database\" [54] collected by the partners and collaborators of the European metrology project EURAMET EMPIR 15 SIB07 PhotoLED consisting of more than 3000 SPDs of commercially available LEDs. These databases include LEDs of different technologies: phosphor-converted LEDs (pc-LEDs) and color-mixing LEDs (cm-LEDs). In general lighting applications, the pc-LEDs are the most widely used technology [55]. The pc-LEDs with nominal CCT of 3500 K (91 pcs), 4000 K (256 pcs), 4500 K (33 pcs), and 5000 K (36 pcs), and CRI Ra values consistent with the requirement of medical examination rooms (Table 1) were selected, representing a total number of 416 different LEDs. The SPDs and chromaticity coordinates (represented by colored dots) are shown in Figure 4. The magenta and yellowish dots are for LEDs that are compliant with the Australia/New Zealand requirements, where CCT is in the range of 3300 K-5300 K. Magenta dots are used to represent LEDs with nominal CCT in the range of 4000 K-5000 K. The (\(R_{f}\), \(R_{g}\), and \(R_{cs,h1}\)) parameters of these LEDs are shown in Figure 5. The number of LEDs belonging to each CPC class is presented in Figure 6.  
Figure 4: (**a**) SPDs of commercially available LED light sources and (**b**) chromaticity coordinates of these LEDs. The area with nominal CCT values according to 7-step quadrangles is delimited by black dashed lines. The magenta and yellowish dots correspond to LEDs applicable in Australia/New Zealand, for which CCT is in the range of 3300 K–5300 K. Magenta dots correspond to LEDs in a nominal CCT range of 4000 K–5000 K.  
The CRI Ra values of the tested LEDs are plotted as a function of the CPC class in Figure 7. Figure 8 shows the CCT values. Figures 7-11 represent the values of a specific parameter for all the tested LEDs according to the corresponding CPC class. In Figures 7 and 8, the magenta and yellowish dots represent LEDs applicable in Australia/New Zealand (3300 K \(\leq\) CCT \(\leq\) 5300 K). Magenta dots are only for LEDs satisfying 4000 K \(\leq\) CCT \(\leq\) 5000 K), such as those required for healthcare lighting in Europe, the United Kingdom, and the United States. The COI values of the LEDs under consideration are presented in Figure 9. Figure 10 shows the LER values. The values of CRI R\({}_{9}\) for these pc-LEDs are presented in Figure 11, while Figure 12 shows the \(R_{f,skin}\). Figure 5: (**a**) \(R_{f}\), (**b**) \(R_{g}\), and (**c**) \(R_{oS,H1}\) values of the LEDs under consideration. The magenta and yellowish dots are for LEDs, which are applicable in Australia/New Zealand, where CCT is in the range of 3300 K–5300 K. The magenta dots are used for the LEDs with a nominal CCT in the range of 4000 K–5000 K, which are applicable in the European Union, United Kingdom, and United States. Figure 6: The number of selected LEDs according to their nominal CCT value and CPC class, where (**a**) is for 3500 K nominal CCT, (**b**) is for 4000 K nominal CCT, (**c**) is for 4500 K nominal CCT, (**d**) is for 5000 K nominal CCT. Figure 8: The CCT values of the LEDs under consideration, according to their CPC classification. The magenta and yellowish dots represent the LEDs, which are applicable in Australia/New Zealand, where CCT is in the range of 3300 K\(\sim\)5300 K. The magenta dots are for LEDs with a nominal CCT in the range of 4000 K–5000 K, which are applicable in the European Union, United Kingdom, and United States. Figure 7: The CRI Ra values of the LEDs under consideration according to their CPC classification.