Characterization of hazardous and odorous volatiles emitted from scented candles before lighting and when lit

•Emission patterns of volatiles from scented candles are assessed in a number of respects.•Compositional changes in volatiles are found considerably before lighting and when lit.•Strikingly, exposure levels of some species are high enough to exceed guideline values.•Scented candles can be significant emission sources of volatiles in indoor environment. Scented candles are known to release various volatile organic compounds (VOCs) including both pleasant aromas and toxic components both before lighting (off) and when lit (on). In this study, we explored the compositional changes of volatiles from scented candles under various settings to simulate indoor use. Carbonyl compounds and other VOCs emitted from six different candle types were analyzed under ‘on/off’ conditions. The six candle types investigated were: (1) Clean cotton (CT), (2) Floral (FL), (3) Kiwi melon (KW), (4) Strawberry (SB), (5) Vanilla (VN), and (6) Plain (PL). Although a large number of chemicals were released both before lighting and when lit, their profiles were noticeably distinguishable. Before lighting, various esters (n=30) showed the most dominant emissions. When lit, formaldehyde was found to have the highest emission concentration of 2098ppb (SB), 1022ppb (CT), and 925ppb (PL). In most lit scented candles, there was a general tendency to show increased concentrations of low boiling point compounds. For some scented candle products, the emission of volatiles occurred strongly both before lighting and when lit. For instance, in terms of TVOC (ppbC), the highest concentrations were observed from the KW product with their values of 12,742 (on) and 2766 ppbC (off). As such, the results suggest that certain scented candle products should act as potent sources of VOC emission in indoor environment, regardless of conditions – whether being lit or not.