The prevalence of cannabis vaping, especially among young people, continues to outpace the understanding of its impact on public health. The frequency of vaping cannabis among adolescents from all demographic groups was recently reported as ≥ 6 times per month, and is rising faster than occasional use. Cannabis concentrates (CCs), also termed extracts or oils, are among the most common and potent cannabis vaping formulations. CCs are typically highly enriched in cannabinoids such as THC or CBD. THC concentrations in CCs are ~50-90% (w/w), while the THC content in cannabis plant material for smoking is 10-25%. Currently, the number of new CC formulations continues to grow, including the emergence of previously unknown semi-synthetic cannabinoids, many of which are currently legal and readily available. The overarching goal of this project is to bridge significant knowledge gaps including understanding how specific chemical formulations and vaporizer designs exacerbate toxicant formation. To address these issues, new analytical methodology will be developed to determine the origins of toxic emissions. A main toxicant prioritized for study in the application is ketene, a violently reactive, potentially deadly poison gas with high pulmonary toxicity. The specific aims of the proposed study are: 1. Determine chemical sources of ketene emissions during vaping 2. Determine the device-related parameters that modulate toxicant emissions.