Occupational exposure limits for blue light in welding environments: Based on ICNIRP guidelines and human eye imaging principles

Background Blue light, as an occupational hazard, is widely present in welding and related work environments. However, China's occupational health standard system has not yet established any limit for blue light exposure in welding work environments.

Objective To study and propose blue light exposure limits in welding operation environments, and provide a reference for evaluation of blue light hazard and maximum allowable exposure time in welding operations.

Methods A function between retinal irradiance and welding arc radiance was introduced by studying arc light and blue light radiation generated in welding operation environments, analyzing the incoherent light radiation protection guidelines issued by the International Commission on Non-Ionizing Radiation Protection (ICNIRP), and combined with factors such as the size of arc light in welding operations, the distance between the welder's eyes and the arc light, and the diameter of the human eye pupil, as well as the geometric optics principle of human eye imaging and the conservation of energy. Then, the radiance limit (100 W·m⁻²·Sr⁻¹) issued by ICNIRP was input into the above function to calculate the blue light irradiance exposure limit in the welding operation environments.

Results The blue light irradiance exposure limit in the welding operation environments ( E_\rmB^\rmEL ) was 3 W·m⁻². Considering the high repeatability of welding operations, the exposure limit for blue light radiant exposure ( H_\rmB^\rmEL ) was 60 J·m⁻². According to the definitions of radiant exposure and irradiance, the maximum allowable exposure time within one working day was calculated according to the formula t_\mathrmm\mathrma\mathrmx=H_\rmB^\rmEL/E_\rmB , in which E_\rmB was the measured blue light irradiance in a welding environment.

Conclusion Exposure limits of radiant exposure for blue light are proposed to provide important references for evaluating the hazards and maximum allowable exposure time of blue light in welding operations, and for future development of occupational exposure limit standards for blue light in China.