Incense was burned in a controlled environment, in order to understand the effect of relative humidity on polycyclic aromatic hydrocarbons (PAHs) emissions from smoldering incense. The concentrations of individual PAHs were determined using the GC/MS analysis method. Incense was burned in a test chamber with a total airflow rate of 6.0 L/min, with relative humidity of 21.3 ± 1.0, 51.0 ± 0.2 and 90.5 ± 0.5%, at a constant temperature (28.9 ± 0.4°C). The results show that the rate at which the incense burns decreases linearly as the relative humidity increases, at the tested airflow rate. The sums of the total PAH and toxic equivalency emission factors for particulate and gas phases were 47467.39–50218.87 and 325.21–358.85 ng/g, for the incense used in this study, and these values also decrease as the relative humidity increases. The carcinogenic potency of PAHs emissions in the particulate phase is approximately 6 times higher than those of the gaseous phase, at the relative humidity tested.