- 期刊
氮氣窒息－密閉空間作業之致命性危害
Nitrogen Asphyxia - A Potentially Fatal Hazard to Confined Space Worker
摘要
氮氧為無色、無臭、無味之惰性氣體，在工業及醫學上有廣泛的用途。本身對人體的直接危害很小，但當濃度升高造成空氣中氧氣濃度下降至19.5%以下時，會形成缺氧的環境，產生窒息作用。我們報告某化學工廠，由於雇主、勞工及外包廠商對作業環境的可能危害，缺乏警覺性，因此連續發生兩次氮氣窒息事故。 事故一發生於84年某日，在某苯乙烯一丁二烯合成橡膠乳液化學工廠，發生二人窒息事件。事故發生地點為已輸入氮氣之聚醚多元醇(polyether polyol)反應槽，工廠之二位勞工欲檢拾掉入之桶蓋而昏迷於槽內。兩人在短時間內被救出，經初步急救及住院治療後，病人分別於四日、八日後出院。事故二發生於85年某日，同一工廠之外運承攬商及司機二人，將氮氣管線誤為壓縮空氣管線而將氮氣導入橡膠乳液成品運送槽車內，隨後於清洗槽車時昏迷於車內，另二位員工前往救援時，未佩戴呼吸防護具，也立即昏迷於槽車內，而後才由安全人員穿戴供氣式呼吸防護具將四人救出。經急救後，二人到院死亡，另二人轉院治療。二人最初的表徵為昏迷及呼吸微弱，隨後程現極度躁動、胡言亂語。給予鎮靜劑、氧氣等支持性療法後，個案分別於第15及19小時清醒，但清醒後均有前行性記憶喪失(antegrade amnesia)，對事發經過完全失憶而其他記憶則正常。 此二件事故發生主因1.安全衛生教育訓練未能落實，勞工對作業環境可能潛在的危害未充分瞭解；2. 貯槽及槽車均為密閉空間，進入前未實測環境之有害化學物暨氧氣濃度；3. 標示不清，導致誤接氮氣管線；4.救援時，未先請求支援及佩載呼吸防護具，以致造成更多受害者。密閉型空間的作業在化學工廠經常可見，勞工安全衛生法對缺氧環境作業，已有明確規定。但由此事故可以了解工業安全衛生管理的執行有待落實之處猶可多。我們報告此事故，探討其發生原因、提出預防對策及討論密閉空間及橡膠作業之可能危害，以作為工廠安全衛生管理及勞工主管機關擬定政策及執行管制的參考。
並列摘要
Nitogen is a colorless, odorless inert gas which has been widely used in industry and medicine. Nitrogen content is 78% in air, there is no harmful effect at this level. However, it may displace the oxygen in breathing air to a level of below 19.5%, leading to simple asphyxia. As nitrogen asphyxia is less recognized as a work-related hazard, we report two incidents of nitrogen asphyxia which caused 2 death and 4 injury in confined space working. Incident 1, occurred in 1995, two workers of a styrene-butadiene latex manufacturing factory were found unconscious soon after entering a nitrogen-filled polyether polyol tank. The were survived with aggressive oxygen therapy. Eight months later, two workers of the same plant were found comatose in a latex transporting tank-truck which was later found to have been misconnected to a nitrogen air-pipe. Another two workers fell into unconsciousness while rescuing them without air-supplying respirator. After initial resuscitation, two workers died and the other two presented with agitation and disorientation. Endotracheal intubation with appropriate sedation was provided. Both recovered well except the presence of antegrade amnesia. Field investigation revealed that these incidents were related from the following deficits: 1. unawareness of potential risk of confined space; 2. failure of measuring for oxygen & hazardous chemicals before entering confined space; 3. without appropriate labeling leading to misconnection of nitrogen-pipe to tank-truck; 4 improper rescue procedure without wearing procedure without wearing protective respirators. Failure of measuring the concentration of hazardous chemicals before entering the confined space was the main causes of both accidents. Although the safety practice at confined space has been regulated for many years, nevertheless, tragic accidents related to improper protection continues to occur islandwied. To avoid the occurrence of such accidents, workers on-job training for safety practice, improvement of working environment, exercise of air monitoring before entering confined space are critically important.