Trace contaminants originating from both material off-gassing and human metabolism may cause human safety and welfare issues, when they accumulate in the spacecraft cabin air. For long duration missions and planetary bases, biological oxidation is a viable solution for the removal of these contaminants. The Biological Air Filter, BAF, a development of Stork and Bioclear is a continuously operating system, which degrades trace organic contaminants to harmless components like water and CO2.The BAF forms an interesting alternative to the existing physical-chemical trace contaminant control systems. This ecological system is low in weight, volume and power consumption. Due to the nature of the system, the maintenance requirements are also very limited. The applied micro-organisms are harmless and the system is operated at atmospheric pressure, which makes the system extremely safe within the operating environment. This paper presents Biological Air Filtration as an alternative for trace gas contamination control on ISS.