Generation rates and emission factors of particulate matter and particle-bound polycyclic aromatic hydrocarbons of incense sticks

The generation rates and emission factors of particulate matter and associated polycyclic aromatic hydrocarbons (PAHs) from incense burning were assessed in a laboratory setting. The differences among different segments of the same stick, among different sticks of the same kind of incense, and between two kinds of manually made Chih-Chen incense sticks (A and B) were evaluated. Joss sticks were burned inside a 44 cm long elutriator; personal environmental monitors fitted into the top of the elutriator were used to take PM2.5 and PM10 samples of incense smoke. Samples were analyzed for PAHs by gas chromatography–flame ionization Detector. It was found that particle and associated PAHs were generated approximately at 561 μg/min (geometric standard deviation (GSD)=1.1) and 0.56 μg/min (GSD=1.1) from Incense A, and at 661 μg/min (GSD=1.7) and 0.46 μg/min (GSD=1.3) from Incense B, respectively. One gram of Incense A emitted about 19.8 mg (GSD=1.1) particulate matter and 17.1 μg (GSD=1.2) particulate-phase PAHs, while one gram of Incense B produced around 43.6 mg (GSD=1.1) of particles and 25.2 μg (GSD=1.2) of particle-bound PAHs. There were significant differences in emissions between Incenses A and B, although they belong to the same class of incense. A 10–20% variability in emissions was observed in the main part of the manually produced stick, and a larger variation was found at both tips of the combustible part.