Field surveys of the effect of lamp spectrum on the perception of safety and comfort at night

Public lighting improves visibility and provides orientation. It also contributes to the perception of comfort and safety of people outside after dark. At present, highpressure sodium lamps are widely used in street lighting. This is in part due to their high efficacy and relatively long lifetime (>= 16 000 hours). Their use, however, comes at the expense of good colour rendering. Recently developed ceramic metal halide lamps provide many of the advantages of HPS in addition to white light and better rendering of colours. In this paper, results of research conducted in three European countries on the effect of lamp spectrum on face recognition and the perception of safety and comfort outdoors are presented. The results consistently show that at comparable illuminances, people perceive areas illuminated with white light to be brighter, safer and more comfortable than the same neighbourhood illuminated with yellowish light.