An understanding of the various source of non-methane volatile organic compounds is one facet to ensuing the habitability of crewed spacecraft. Although the International Space Station (ISS) atmosphere is relatively well characterized in terms of what is in it and approximately how much, linking the majority of these trace contaminants detected to their source is virtually impossible. Albeit a few of the trace contaminants can be associated to a single source, the majority have their origins from multiple sources. On crewed spacecraft such as ISS, trace contaminants are broadly categorized as either coming from equipment, which includes systems and payloads, or from the metabolic process of the crew members. Such widely encompassing categories clearly illustrate the difficulty in linking air contaminants to their source(s). It is well known that microbial growth in ISS can flourish if left unchecked. Although processes are in place to limit microbial growth, in reality, it has pervaded the habitable environment of ISS. This is simply a consequence of having crewed spacecraft, as humans are the largest contributor to the bioload. As with crew members, microbes also have metabolic processes that, in many ways are comparable to human metabolism. As such, it can be expectant that microbial growth can lead to the release of cortile organic compounds (VOCs) into the ISS atmosphere. Given a large enough microbial population, the impact to the air quality of ISS can be potentially large. A survey of the microbiology found in ISS will be presented here as well as the possible types of VOCs that can result from such organisms. This will be correlated to the observation provided by ground-based analysis of ISS atmosphere samples.