The present invention relates to a sealing system, its uses and method of use for forming a seal against a surface, and in particular for plugging and sealing an orifice such as a road or railway tunnel to prevent or minimise the dispersion of hazardous agent(s) in an emergency scenario. The system comprises a frame (200) which can be orientated against a surface (50) of an orifice, frame (10) comprising a perimeter outer surface (180) through which pliant elements (40) can extrude, via apertures (22), following the initiation of a means (30) for providing an overpressure.