An air separation system includes an air separation module configured to receive feed air and separate the feed air into nitrogen-enriched air and oxygen-enriched air, a nitrogen-enriched air line for transporting the nitrogen-enriched air from the air separation module to a fuel tank for inerting, an oxygen sensing line connected to the nitrogen-enriched air line, a gas adsorption filter located in the oxygen sensing line, and an oxygen sensor downstream of the gas adsorption filter in the oxygen sensing line.