3. Evaluation of Artificial Light with Respect to Human Health

After having illustrated in the second chapter the various relationships existing between light and human physiology, the focus here is on the quantitative aspects of light, which can be used as part of the requirements of the lighting design methodology, which may have NIF effects on the organism. The emphasis is placed on the dose-effect relationships that can come into play in human centric lighting, as positive or negative elements, and on possible sources of risks, with particular reference to LED light. These elements include consolidated requirements of lighting design, such as the control of glare and of the temporal modulation of light, which are now applied to LED lighting. A further topic of reflection, which has seen a lot of interest by the press, concerns the presumed photobiological hazard related to LED lighting. Finally, starting from the assumption that melatonin is the main marker able to detect the state of the human circadian cycle, this chapter introduces the basic elements for the possibility of defining a circadian photometry that can support the activity of the lighting designer, evaluating the current state of the research in this regard.