电脑显示器极低频磁场的强度分析

目的　研究电脑阴极射线管显示器正前方不同距离和不同方位的极低频磁场(ELFMF)强度 ,就如何减少ELFMF的影响提出初步建议。方法　测定 2 0 0台阴极射线管显示器及10台液晶显示器的ELFMF强度。在显示器正前方距离 0～ 5 0cm ,每隔 5cm设一测定点 ,各点测定3次 ,并测定显示器不同方位 0cm处的磁场强度。结果　 38cm和 4 3cm两种阴极射线管显示器在操作电脑的习惯性位置 (30～ 4 0cm)的ELFMF强度比屏前 0cm处有明显衰减。 38cm显示器在屏前 15cm以内的ELFMF强度超过 0 4 μT ,4 3cm显示器在 10cm以内其强度超过 0 4 μT。两种显示器不同方位的测定结果显示 ,以显示器正上方的强度最大 ,38cm显示器为 (9 5 4± 0 16 ) μT ,4 3cm显示器为 (6 38± 0 16 ) μT。 结论　建议使用电脑时与显示屏保持一定的距离 ,尽量减少视频前的持续操作时间。加大各台电脑之间的距离 ,避免其相互间的干扰对人体产生更大的危害。

Assessment of exposure to extremely low frequency magnetic field emitted from monitors

OBJECTIVES: To investigate intensity of extremely low frequency magnetic field (ELFMF) emitted from cathode-ray tubes (CRT) of monitors in various directions and to find ways to avoid its influence. METHODS: Two hundred CRT monitors and 10 monitors with liquid-crystal display (LCD) were selected. Their ELFMF was detected for three times in front of the monitor at an interval of every 5 cm from 0 cm to 50 cm, as well as at various directions from the monitor. RESULTS: Intensity of ELFMF significantly attenuated at regular operating position (30 - 40 cm) from 0 cm to 50 cm in front of both 38 cm and 43 cm CRT monitors (P < 0.05). Intensity exceeded 0.4 microT both within 15 cm and 10 cm in front of 38 cm and 43 cm monitors. The highest intensity was found at the upright top position of both kinds of monitors, 9.54 microT for 38 cm monitor and 6.38 microT for 43 cm one, respectively. CONCLUSIONS: It is suggested to keep away from monitor screen as possible when operating a computer, to reduce unnecessary operation in front of a monitor screen, and to shorten operating time. To avoid more hazards from interactive interference between computers, it is necessary to increase distance between monitors.