Characteristics comparison of gaseous and particle-phase VOCs released by smoldering mosquito coils and their health risks

Abstract

Mosquito coils have been widely used in tropical and subtropical regions, particularly in rural areas. However, their emissions, primarily volatile organic compounds (VOCs) and particulate matters (PMs), have raised concerns about their potential health impact. This study provides new insights into the characteristics of VOCs and PMs produced by three representative Chinese mosquito coils, revealing stark differences in VOCs found in the gas phase compared to the particle phase. Results showed that during the use of mosquito coils, the indoor concentrations of total volatile organic compounds (TVOCs) and PM2.5 can surge to 2.35–3.33 times and 1.59–7.42 times above the acceptable standards, respectively. Detailed characterization of VOCs using GC/MS suggested that PMs concentrations significantly impact the distribution of VOCs in gas and particle phases. A key finding of this study is the difference in VOCs composition between the gas and particle phases. The particle phase VOCs demonstrated a higher species number and average relative molecular weight across the three tested mosquito coil brands, and the carcinogens they contained were entirely distinct from those found in the gaseous phase. For instance, gaseous VOCs were predominantly alkanes (60.29–74.75 wt%), while the dominant particle-phase VOCs for the three mosquito coils were alkanes (33.56 wt%), esters (51.76 wt%) and aromatics (35.51 wt%), respectively. Health risk assessments indicated that while gaseous VOCs contribute predominantly to both non-carcinogenic and carcinogenic risks, the role of particle-phase VOCs, particularly from mosquito coils producing more PMs, cannot be discounted. This study conducted a detailed evaluation of the various forms of pollutants generated by mosquito coils, providing crucial references for future assessments of pollution emanating from similar sources.