Emission rates of particle-bound heavy metals and polycyclic aromatic hydrocarbons in PM fractions from indoor combustion sources

Indoor combustion sources significantly affect the air quality in homes, emitting both airborne particles and related particle-bound chemical compounds, such as heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs). The emission of particle-bound HMs and PAHs from indoor sources has been poorly investigated by the scientific community. This paper aims to fill this knowledge gap by providing emission rates of particle-bound HMs and PAHs in various PM fractions (PM1, PM1-10, and PM10) from typical indoor combustion sources: incense, candle, and mosquito coil combustions and cooking activities. To this end, two experimental analyses were carried out to obtain (i) the emission rates of PM fractions and (ii) the mass fraction of each particle-bound HM and PAH in the PM fractions. Results of the study revealed high PM fraction emission rates, with a significant contribution of PM1 fraction, and high HM and PAH mass fractions with a main contribution of the sub-micrometric range (from 61 % to 100 % for Group 1 carcinogenic compounds). The emission rates of HMs and PAHs were determined based on these measurements, with Group 1 carcinogenic compound emission rates in PM10 ranging from about 3 to >100 ng min−1. Using the emission rate data, indoor concentrations and the corresponding non-carcinogenic and carcinogenic lifetime risks for a typical daily exposure scenario were estimated. The expected concentrations from the use of the investigated sources were higher than those typically measured in homes, and significant carcinogenic risks were associated with the use of sources emitting Group 1 carcinogenic HMs.