電弧電焊產生之紫外線量測與暴露評估

Exposure Monitoring of Ultraviolet Radiation from Arc Welding Processes

紫外線作業現場勞工因紫外線所造成的威脅及傷害日漸增加，因紫外線具高能量、高穿透率、對人類的組織器官有很強的殺傷力。目前國內尚未有針對作業場所紫外線輻射強度之量測、調查、各項暴露風險評估及各種防護措施之方法與研究，由於未有一公正客觀的紫外線偵測程序及方法可供相關單位檢驗。本研究將針對電焊作業場所紫外線高劑量輻射進行偵測及暴露評估。利用輻射光譜儀（Spectroradiometer）掃描記錄電焊產生之紫外射線，定性輻射圖譜並作強度積分計算來進行相關之暴露評估。電焊形式採交流電焊（AC Arc Welding），機器電流設定 200A，實際量測電流值介於 85~95A，以焊條 E6011 （4.0mm），依不同距離 50 cm、100 cm、200 cm、300 cm，防護面罩 （50 cm） 與手套 （50 cm），監測 15 秒連續記錄 230~400 nm 之輻射強度（Irradiance），並紀錄光源功率（µW/cm2 ）對波長 （nm）數據，利用 ACGIH 加權公式探究有效輻射（Effective Irradiance）的轉換計算，及觀察電焊時間圖譜的動態變化。結果發現電焊產生瞬間強烈不穩定之光輻射，涵蓋 UVA，UVB，及 UVC 波段。隨距離增加，UVA 在空氣介質中具較佳的穿透性，防護具可有效阻隔 UVA。在 50 cm 處持續性的電焊作業時，15 秒量測之平均有效輻射量為 154.9µW/cm2 ，最大可容許暴露時間為 19.37 秒。50cm 距離穿戴防護衣具， 15 秒量測之平均有效輻射量下降至 7.83 µW/cm2 （面罩）及 3.61 µW/cm2 （手套），最大容許暴露時間分別為 383.1 秒及 831.7 秒。然而，電焊操作卻往往更接近本研究量測之最短距離，因而對操作者將具有極大的危害風險。本研究將提供對電焊作業的紫外線暴露量測與評估的方法，並由量測數據建議電焊勞工應確實穿戴防護器具，及避免連續長時間的電焊作業。

Injuries and diseases due to UVR exposure have been increasing recently with the frequent use of UVR in workplaces. The measurement of UVR strength and evaluation of UVR exposure are the key factors in controling UVR in workplaces. This study establishes a comprehensive approach to the monitoring of UVR magnitude, evaluation of the performance of the approach, and quantification of effective exposure based on measuring data. An ultraviolet spectroradiometer was used to measure UVR emitted from arc welding processing. The spectral weighting function for UVR measurement and evaluation is derived from ACGIH and utilized in this study. The welding machine was set up with 200A electric current (actual electric currents between 85~95A) and using electrodes E6011 (4 mm). Arc welding scattered bright light with strong and unstable UVR emissions covering the entire UV spectrum (UVA, UVB, and UVC). Results show that the effective irradiance at a distance of 50 cm from the arc with 15 seconds of continuous welding is 154.9 mW/cm2 and that the maximum allowable time of exposore (Tmax) is 19.37 seconds. Distance is an important factor affecting irradiance intensity. Shield materials (such as a mask and gloves) can prevent UVR exposure, especially for UVA. The effective irradiances of workers wearing masks and gloves at a distance of 50 cm are reduced to 7.83 and 3.61 mW/cm2, respectively. The Tmax values for workers wearing masks and gloves are 383.1 and 831.7 seconds, respectively. It is possible that welders have a high risk of UVR exposure because most of the arc strikes are less than 50 cm away during welding processing. This study developed a methodology for UV monitoring. The information collected from the welding UVR monitoring data strongly suggests that those whose work is related to welding processing must be provided with appropriate protection.