Abstract: A biosoluble glass fiber filtration media includes a fibrous filtration layer of randomly oriented, entangled glass fibers which has an initial efficiency of 25% or greater as measured by ASHRAE 52.1 test method. The glass fibers forming the media have a biodissolution rate in excess of 150 ng/cm2/hr and a mean diameter between about 2.5×10−5 inches and about 11.0×10−5 inches. Typically, the filtration layer has a thickness ranging from about 0.12 inches to about 0.35 inches and a density ranging from about 3.0 g/ft2 to about 8.0 g/ft2. The filtration has an initial pressure drop of about 0.35 inches of water or less and a dirt holding capacity of about 1.5 g/ft2 or greater.