Tracking indoor volatile organic compounds with online mass spectrometry

Humans spend most of their time indoors, where they are exposed to many volatile organic compounds (VOCs). Exposure to indoor VOCs has been linked to adverse health effects, and so a comprehensive indoor air quality assessment requires a strong fundamental knowledge of indoor VOCs. The recently developed advanced online mass spectrometry enables fast, non-targeted measurements for VOCs, which provides a powerful tool to track the complex indoor VOCs. This review article summarizes the principles of different online mass spectrometry techniques and their application to indoor VOC measurements. The sources, emission characteristics, and chemical compositions of primary indoor VOCs are discussed. Recent advances in the fundamental understanding of chemical transformations and formation mechanisms related to secondary indoor VOCs are also discussed. By summarizing the current advances and remaining challenges for the investigation of indoor VOCs, we propose future research directions regarding their origin, transformation chemistry, environmental fate, and health impact.