In an apparatus and method of forming fibers from a fiberizable material, a molten fiberizable material is introduced into a rotating fiberizing rotor and passed through a plurality of holes in an annular peripheral sidewall of the fiberizing rotor to form primary fibers from the fiberizable material. The primary fibers are introduced into hot combustion gases and pressurized air in a fiberization zone adjacent an outer surface of the annular peripheral sidewall of the rotary fiberizing rotor to attenuate and form the primary fibers into fibers of the desired diameter and length. The hot combustion gases are discharged from an annular air cooled burner and the pressurized air, which is discharged from an annular air ring, is the same pressurized air used to cool the annular air cooled burner.