This procedure allows the assessment of risks arising from exposure to artificial optical radiation in the presence of lamps intended for general lighting, be they intended for offices or for larger environments such as industrial warehouses. In all these cases, the radiation emitted is substantially white light, even if of different tonalities, and staring directly into the source is not part of the visual task of the operators.
In principle, these sources, as intended for lighting the environment, should never represent a risk to the exposed persons. However, the rapid development of innovative technologies for lighting, and in particular of LED and metal halide systems, that occurred in recent years, has raised the problem of the photobiological hazard associated with the emission of blue light, that is potentially detrimental to the retina. In particular the potentially harmful sources are represented by LED and metal halide lighting systems. All the other lighting systems do not present any photobiological risk and, consequently, can be considered "trivial" in the framework of risk assessment.
The IEC safety standard specifications for the lighting systems are currently being adapted in order to introduce, for each type of source, specific emission limits that ensure its safe use in relation to eye hazard. However, at present, manufacturers do not provide information suitable to ensure the photobiological safety of commercial systems for the workers and for the general public . Thus, considering the current lack of legislation, which does not allow to estimate a priori the actual risk of the commercially available systems, and considering their potential harmfulness, we have developed the following procedure, that is suitable to assess the actual risk associated to LED and metal halide illumination sources in an environment, on the basis of the lighting engineering and installation features of the sources themselves.
The result is expressed as 3 risk levels: low-, moderate- and high-risk, according to the following criteria:
Low-risk: No photobiological hazard. “Exempt” source for the purposes of the Directive
Moderate-risk: Compatible with the limit values associated with the Group 1 (IEC EN 62471:2009: no photobiological hazard under normal conditions of use). It could entail a risk if stared into for more than a period of 100 seconds cumulated in the day.
High-risk: The exposures are higher than the maximum ones acceptable for Group 1 (IEC EN 62471:2009). Presence of a risk, even for staring times lower than 100 seconds.
The result of the calculation should always lead to a situation of “low” risk, because a system intended for general lighting purposes must be chosen so that its optical emissions entail a negligible risk from the point of view of the photobiological safety.
If the risk is “ moderate” alternative solutions for installation should be found.
If the risk is “high” there is an improper use of the sources, because the photobiological hazard is not negligible. In this case, alternative solutions in the choice of sources and/or in the modes of installation should be found.
The comparison between the results obtained by the procedure of calculation and the results of the experimental measurements performed in the laboratory has shown that the procedure herein presented is a suitable instrument to assess the actual risk associated with the LED and metal halide illumination sources, by using their main lighting engineering features. It is an easy to use instrument, that allows to carry out the estimation of the risk, even in the absence of specific expertise, that would be requested if the assessment should be carried out by specific measurements of the radiometric quantities.
The detailed methods and the algorithms used are described in detail in the attached documents. (download PDF). They are based on the methods defined in the technical report IEC/TR 62778 and 1.0 (2013) Application of IEC 62471 for the assessment of blue light hazard to light sources and luminaries.