• Project number: F 2483
• Institution: Federal Institute for Occupational Safety and Health (BAuA)
• Status: Completed Project

Description:

Retinal damage caused by light with high proportions of blue in it (blue light hazard, BLH) from display screens and general lighting can be ruled out as a matter of principle provided that employees’ viewing behaviour is natural. By contrast, high-power spotlights used for structural and civil engineering, in the events sector, or at large storage areas represent a potential BLH source.

A BLH risk assessment is usually demanding  - not at least because in many cases radiances have to be determined. Therefore, the aim of this project was to develop a practical, simplified BLH risk assessment method.

The inter-comparability of the optical instruments used, typically integrating and spectral radiometers, is of initial interest before the suitability of such an approach can be evaluated. Although the measurement scenarios were made increasingly demanding in three steps, the measured values had a standard deviation lower than 10%, meaning they were largely independent of the source complexity. A less than 20% standard deviation was found when the practical assessment procedure (Planck Approximation) was verified - a satisfactory result in the context of DIN EN 14255-2. The Planck Approximation is based on a single illuminance measurement, which is converted into the BLH-weighted radiance using the diameter of the spotlight’s radiating surface and a known factor for a blackbody radiator. It was possible to derive three simple equations for the maximum permissible exposure duration as a function of the angular subtense of the source, taking various influencing factors into account. When these were used in practice, the level of accuracy achieved was roughly ±30%. The fundamental applicability of the Planck Approximation for the assessment of blue light hazards has therefore been demonstrated.