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1·The possibility of suck-back of fume cupboard exhaust gases into building air intakes, open Windows or the breathing zone of people working on the roof or in other buildings should be investigated.

应该调查通风橱废气回吸至房屋内的进风口、打开的窗户或者房顶工作人员的呼吸区域或者其它房屋的可能性。