Investigating particles, VOCs, ROS produced from mosquito-repellent incense emissions and implications in SOA formation and human health

Mosquito-repellent incense is popular for dispelling mosquitos indoors in Asia, Africa and South America. However, the released large amounts of particulate and gaseous pollutants have a negative effect on human health. We conducted real-time measurements in laboratory chamber to characterize the particulate matter, volatile organic species (VOCs), reactive oxygen species (ROS) released from the Disc and Liquid mosquito-repellent incenses using. And further to evaluate the secondary organic aerosol (SOA) formation potential indoors attributed to the main VOCs species and the health exposure risk. Results show that the disk type produces more particles but less VOCs. The particle number concentration produced by the disc and the liquid types were 130085 part/cm³ and 7963 part/cm³, respectively. The former one concentrated at the size bins below 100 nm, in comparison with the latter one mainly between 100 and 500 nm. Burning disk type produced particles carrying much higher oxidative potential (OP) 0.0430 nmol/mg. The VOCs species produced by the disc and liquid types were mainly VOC to m/z 79(benzene) and VOC to m/z 33(methanol), and the corresponding benzene concentration were 40.7 ppb and 58.6 ppb, respectively, and the methanol concentration was 26.3 ppb and 35.2 ppb, respectively. SOA formation rate related to benzene of liquid type using was larger compared to disk type, which was 0.015 mg/(m³s) and 0.012 mg/(m³s), respectively. The health risk assessment coefficient of the disc and liquid types were 6.2×10⁻⁵ and 9.1×10⁻⁵, respectively, both exceeding the limit of 1×10⁻⁶, indicating mosquito-repellent incenses is harmful to human health.