It has been confirmed by several animal experiments that the exposure of the part of visible light called blue light (wavelength region : approximately 400-500 nm) produces photochemical lesions on the retina. The American Conference of Governmental Industrial Hygienist (ACGIH) recommended an evaluation method of blue-light radiation hazards and threshold limit values (TLVs) based on it : blue-light effective radiance (integrated spectral radiance weighted against bluelight hazard function) of a light source should be measured to evaluate its blue-light radiation hazards and should be compared with the TLV. But very few studies have been made on blue-light radiation hazards in the workplace because suitable methods of measuring blue-light effective radiance have not been developed yet.
In this study, an instrument to measure blue light was developed, and the bluelight effective radiance of welding arcs was determined with it under 14 different welding conditions.
The maximum of the obtained ACGIH blue-light effective radiance is 2.4 W/cm
2-sr of metal active gas (MAG) welding of soft steel, of which the permissible exposure duration per day would be approximately 42 seconds, according to the recommendation of the ACGIH. This is the level at which welders do not suffer retinal injury from blue-light radiation, if they wear an eye protector with a filter suitable for their vision during welding operations, as they actually do in the workplace.
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