The system comprises: a mixture including a polysaccharide having a molecular weight of between about 50,000 and 1.5???106 Daltons at a concentration of less than about 5.0 mg/ml (w/v) of polysaccharide, and a breathable fluorocarbon propellant; a cannister adapted to contain the mixture under pressure; a valve connected to the cannister for regulating delivery of the mixture; and a nozzle interco