Plastic baggies seal in condensation leading to possible mold and mildew damage .
Serious collectors and photographers DO NOT rely on Low Density PE zipper baggies for anything but short term protection. Be aware, however, that airborne oils and acids can cause damage AND they increase the 'holding' power of dust. Dust, over time, will actually shred the fibers of fabrics in your collection. Doll clothes and teddy bear fabric alike will eventually show deterioration. Be certain wooden shelves are sealed with an inert sealant - all woods are acidic and contain lignins.