Abstract: An air curtain fume cabinet, in which an air curtain jet is directed across the face opening to an exhaust duct. Sufficient flow is exhausted at the exhaust duct to swallow (i) the entire air curtain jet, plus (ii) all of the air which the jet entrains from outside the face opening, plus (iii) a substantial additional amount of air. This greatly increases the velocity of air moving into the curtain at its top, beyond the normal entrainment velocity, and prevents spill-back of jet air to the outside even with substantial crosswinds. Preferably the ratio of exhaust flow to jet flow is between 2 and 3 for a jet height to jet thickness ratio of up to about 15. Preferably auxiliary air is supplied to the working space interior to replace air entrained into the jet from inside the working space.