NOVELTY - Fiber (I) comprises a porous core (A) and a sheath (B) surrounding (A) where (A) comprises a sorbent and a polymer, where (B) is characterized by a heat resistance of at least 110 degrees C and one or more of: a water vapor transmission rate of less than 50 Barrer at 38 degrees C and 90% relative humidity; an oxygen permeability of less than 10 Barrer; a nitrogen permeability of less than 1 Barrer; or a carbon dioxide permeability of less than 20 Barrer.    USE - (I) is useful for reducing the amount of one or more low level contaminants (sulfur contaminants) of a gas stream comprising natural gas, a petrochemical stream, city gas, diesel fuel, gasoline, liquefied petroleum gas, jet fuel, a reformate gas and/or naphtha (all claimed). (I) is useful for removing contaminants of volatile organic compounds and sulfur compounds form liquid or gas fuels.    ADVANTAGE - (I) is capable of removing low level contaminant from a gas stream both effectively and efficiently.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a multi-layer spinning process for making a sheath on a fiber comprising spinning a sheath dope with a core dope to form (I) comprising (A) and (B) where: the improvement comprises employing a sheath dope composition which comprises a polyvinylidene chloride and a solvent comprising a dipolar aprotic solvent; and the polyvinylidene chloride comprises at least 15 wt.% based on the total weight of the composition; and    (2) a process for reducing the amount of one or more low level contaminants of a gas stream comprising: (a) contacting the gas stream comprising an initial concentration of one or more low level contaminants with (I); where the contacting is conducted in a manner such that the initial concentration of one or more low level contaminants in the gas stream is reduced by sorption of the low level contaminants on the sorbent; and (b) regenerating one or more fibers by passing a regenerating fluid which has a temperature of at least 50 degrees C over the sheath layer of (I) in a manner such that the fluid does not substantially contact (A).