In a previous article, we described the evaluation of several catalyst systems (Pt, Pd, Ni, Pd/Ni) for catalytic removal of O-3, CO, C3H6 (as hydrocarbon), and NO from ambient air. The catalyst evaluation was carried out over the 25-105 degrees C range to address the practicality of using low-temperature catalysts to remove ambient pollutants from urban area as an alternative or in addition to other pollutant control measures. In this article, we address other important properties relevant to the viability of such low-temperature catalysts, namely (1) durability and poisoning, (2) resistance to blocking by ambient moisture, (3) mass-transfer limitations, and (4) efficiency in complex mixtures and the mechanism of pollutant removal.