Minimum illuminance refers to ordinary whole-room lighting in the operating room, and does not include local lighting or shadowless lamp illumination. Both in China and abroad, the light-band type of lighting is widely adopted, and illuminance levels also differ considerably from country to country. According to foreign literature, the general illuminance in operating rooms is mostly above 500lx, with the highest reaching 1 500lx, and some sources have proposed 750～1 500lx. However, according to later field measurements, the illuminance of the aseptic operating room at Tokai University in Japan was 465lx, the preparation room 350lx, and the anteroom 420lx. These data were not explicitly stated to be minimum illuminance, so they are most likely average illuminance. In light of China's national conditions, the Code adopts, for general operating room lighting, the value of the lowest point among all measurement points in the work area, i.e., the minimum illuminance, taken as 350lx; the average illuminance will then also be above 400lx. For non-operating-room rooms, 150lx is adopted in accordance with the minimum standard for cleanrooms.

For general indoor lighting, within 0.5m of the walls, the minimum value at each point on the work surface shall be satisfied.