Abstract: A process and apparatus is described which produces a geometric air projection and containment space tented over an opening in the side wall of a building in which substantially continuous sheets of ambient air are directed outwardly from around said open area into the ambient atmosphere toward a common apex in an axis which projects normally or obliquely from the opening, three said contiguous sheets intersecting at the common apex to form a tent-shaped containment space comprised within a pyramidal-shaped geometric figure, the apex of which is the confluence of the sheets. The walls of the containment space consist of said sheets sufficiently intact to prevent or minimize passage of gaseous material into the containment space except through the open area, and the sheets converge at an angle such that flow is induced into the containment space sufficient to prevent back-flow through the open area.