During the performance of stage productions, actors and the stage itself are illuminated by means of stage lights. High-power spotlights may be used for this purpose that are aimed directly at the actors and track them. Besides visible light, the stage lights also generate an ultraviolet (UV) radiation component that can present a hazard. The hazard presented by blue light must also be assessed.
For the purposes of risk assessment, the limit values defined in the German OSH Ordinance on Artificial Optical Radiation (OStrV) must be observed. The measured values and experience gained to date on the exposure of workers in this context is limited. The Austrian General Accident Insurance Board (AUVA) for example has attached more importance to the actual radiation emission of the stage lights; exposure of the workers (actors, helpers, stage hands, etc.) for the purposes of the OStrV has yet to be determined.
The objective of the project was to assess a range of exposure situations in theatres and to describe typical exposure scenarios. The results were then to feed into a guidance document on risk assessment produced and published by the German Social Accident Insurance Institution for the public sector in Schleswig-Holstein and Hamburg.
Radiation measurements were performed in five theatres falling under the responsibility of the German Social Accident Insurance Institution for the public sector in Schleswig-Holstein and Hamburg. The results were evaluated and prepared in accordance with the OStrV.
The stage light configuration in theatres is dependent upon the size of the stage and also upon the type of production that is being performed. A range of lighting situations and tests also arise during regular rehearsals. The exposure during final rehearsals appears to be representative of the overall situation, however. For organizational reasons, it was not possible for measurements to be taken in the theatres during final rehearsals. Measurements were therefore performed from the location of the actors and other relevant personnel in the direction of the stage lights either before or after a rehearsal.
The results were assessed in accordance with the OStrV. This included analysis of the possible UV radiation exposure and of the hazard presented by blue light. The exposure limits for protection against UV radiation were found to be observed when the stage lights studied are used. Conclusive evaluation of the exposure to blue light was however not possible, since the necessary information on the duration for which the stage light is viewed directly was not available. It was determined however that for hydrargyrum medium-arc iodide (HMI) stage lights in particular, the duration for which the lamp must be viewed directly before the limit is exceeded may be in the order of only a few seconds, whereas with lamps of other types, the limit is exceeded only after long viewing durations. Where a stage light (particularly an HMI stage light) is viewed for a longer period, the exposure limit for protection against photochemical damage to the retina may be exceeded even during a single performance.
The findings are to feed into a larger joint project that is being coordinated by the VBG with the involvement of a number of project partners (VBG, IFA, BAuA, BG ETEM, Hamburg University of Applied Sciences, AUVA, Osram). The aim of further activity based upon these results is consensus-based assessment of any given spotlight configurations in general and at theatre stage workplaces in particular.
servicesType of hazard:
risk assessmentDescription, key words:
UV radiation, blue light, exposure, lighting, stage, theatre