Congratulations to Shuang Wu’s new publication on Royal Society of Chemistry Environmental Science: Processes & Impacts (Link)! In this work, we explored third-hand exposure of common flavourings used in novel nicotine delivery systems, including e-cigarettes and hookah tobacco. Third-hand exposure refers to the exposure to chemicals initially released to the surrounding environment (e.g., indoors). Such exposure pathways have not been carefully studied for e-cigarettes but are highly dependent on chemical partitioning of chemicals of interests. Shuang and Erica performed careful measurement and modeling for carbonyl flavourings commonly used in e-cigarettes. We have also performed a fundamental analysis on the hydrolysis equilibrium coefficients of these carbonyls, which governs their chemical partitioning. Our study shows that many of these flavouring compounds can likely present between indoor air and organic indoor films, and the fraction of which is highly dependent on temperature and the reservoir size. These results show that third-hand exposure for harmful flavourings is likely important and should be studied in depth in the future.