Emissions of Polycyclic Aromatic Hydrocarbons (PAHs) from the Use of Scented Candles Under Different Environmental Conditions

This study investigated the effects of environmental conditions on polycyclic aromatic hydrocarbon (PAH) emissions from scented candles during combustion. An exposure chamber was established and validated to ensure stability and uniformity before the experiments were conducted. One of the most widely used scented candles (paraffin wax + 6% lavender essential oil) was selected in the present study. Testing environmental conditions included three relative humidity (RH) levels (60%, 75%, and 90%) and three air exchange rates (ACHs) (0.5, 1.0, and 2.0 h−1). For each tested environmental condition, three replicate measurements were conducted. Gas-phase and particle-bound polycyclic aromatic hydrocarbons (PAHs) were collected using filter cassettes and XAD-2 sorbent tubes, respectively. Results showed that, under identical RH conditions, both Ctotal-PAHs and EFtotal-PAHs followed the trend of 0.5 ACH > 2.0 ACH > 1.0 ACH, whereas total-Bapeq and EFTotal-BaPeq values decreased with increasing ACH. While under identical ACH conditions, emissions showed a nonlinear response to RH, following the trend: 75% > 90% > 60%. Most detected PAHs were present in the gaseous phase and were dominated by low-molecular-weight compounds containing two to three aromatic rings. The estimated highest incremental lifetime lung cancer risk reached 1.20 × 10−6 for aromatherapy workers, assuming an exposure duration of 8 h day−1 over 40 years. These findings highlight the potential health risks associated with the use of scented candles and emphasize the importance of adequate ventilation to reduce long-term indoor exposure.