Study on a new method for reducing radon level in indoor air

The aim of this study is to develop a new technique for reducing high radon level in indoor air bymethod of membrane permeation using a hollow fiber module. The experiment has been carried outfor MERASILOX-S module of fine hollow fibers of silicon rubber that has high permeability constantand MHF hollow fiber module made of thin segment polyurethane membrane. The radon permeabilityconstants of hollow fiber membranes have been estimated from the decrease rate of radonconcentration in a radon permeation system. The apparent permeability constant depends on the flowrate through the outside and the inside of hollow fibers. The apparent permeability constants ofMERASILOX-S and MHF module membranes were 3.910-9 m2.s-1 and 1.110-9 m2.s-1 at the flowrate above 5.0 L.min-1. However, the permeation velocity of MHF module is grater than that ofMERASILOX-S module. The radon concentration in a 50 m3 room of concrete building could bereduced to about 1/10 by using a MHF module with membrane area of 18 m2. The use of pressuredifferent between the inside and the outside of hollow fibers might be applied to reduce theenvironmental radon concentration.