Characterization And Toxicity Assessment Of Polycyclic Aromatic Hydrocarbons（PAHs） In Particulate Matter PM_1.0 Released From The Combustion Of Mosquito Incense And Moxa Stick

Indoor material combustion is one of the sources of indoor pollution,where mosquito incense and moxa and other substances are typical indoor combustion sources that people are more exposed to.Mosquito incense and moxa burning will release particulate matter and polycyclic aromatic hydrocarbons（PAHs）,which are harmful substances that not only affect indoor air quality but also pose health risks to humans.In view of this,after the test of mosquito incense and moxa burning for many times to release particulate matter in the early stage,it was revealed that the particulate matter PM_1.0dominated.Therefore,this paper focuses on the emission characteristics and influencing factors of PAHs from mosquito coils and moxa strips in PM_1.0and evaluates the toxicity of PAHs in PM_1.0.This has important implications for improving people’s daily use of mosquito coils and moxa and for reducing pollution releases.In this paper,nine types of combustible mosquito incense with different smoke labeling,different base materials and different forms and four types of smoked moxa with different storage years and processing ratios were selected for the study,and the incense and moxa were burned in an 8 m³clean environment chamber with adjusted operating parameters.After the combustion reached equilibrium,the solid phase PM_1.0released from the combustion of mosquito coils and moxa strips were sampled and purified for PAHs,and the content of PAHs in PM_1.0was obtained by GC-MS analysis after purification(referred to as solid phase(PM_1.0)PAHs).Then the emission factors and emission rates of solid-phase(PM_1.0)PAHs released from the combustion of mosquito coils and moxa were determined based on the mass balance equation of indoor pollutants,and the effects of different characteristic parameters inherent to combustion sources on solid-phase(PM_1.0)PAHs were also analyzed,and finally the toxicity of PAHs released from the two types of substances was evaluated.The main findings are as follows:（1）The mass concentrations of particulate matter PM_1.0released from the combustion of the studied mosquito incense and moxa strips in the ambient chamber ranged from 0.789 to3.025 mg/m³and 1.383 to 3.912 mg/m³,respectively.PM_1.0from the combustion of two types of substances dominates.（2）The total emission factors of mosquito coil combustion releasing solid phase(PM_1.0)PAHs ranged from 0.137 to 2.238μg/g·incense,and the total emission rates ranged from0.133 to 9.180μg/h·incense.The emission factor and emission rate of smokeless mosquito incense are higher than those of smokeless mosquito incense.The emission factor and emission rate of mixed-based mosquito fragrances are higher than those of wood-based ones,and the toner-based ones are the smallest.Disc type mosquito incense emitting factor and emitting rate is higher than the line type.（3）Four-ring PAHs are the major part of solid-phase(PM_1.0)PAHs,accounting for30.6%to 58.9%.The percentage of five-ring ranged from 15.2%to 38.4%,and the remaining rings accounted for a smaller percentage.Tricyclic PAHs are strongly influenced by the characteristic parameters of mosquito coils.Individual Phe and Bbf were the dominant individuals.The percentages were 6.3%～45%and 11.1%～33.2%,respectively,and the remaining individuals accounted for a relatively small percentage.Phe was more influenced by mosquito characterization parameters.（4）The total emission factor of PAHs from moxa combustion in solid phase(PM_1.0)ranged from 0.079 to 0.311μg/g·moxa,and the total emission rate ranged from 0.737 to 3.301μg/h·moxa.The emissivity factor and emissivity rate were greater for moxa with smaller years or smaller processing ratios.The effect of processing ratio on the emissivity factor and emissivity rate was more obvious.（5）The proportion of three-ring PAHs in the solid phase((PM_1.0)PAHs released from the combustion of moxa strips was the largest,with 41.9%～48.1%.The proportion of tetracyclic PAHs was 32.9%～47.4%,and the proportion of the remaining ring PAHs was mostly below 10%.The proportion or the year of the smaller moxa produced a greater proportion of pentacyclic and hexacyclic PAHs.Individual Phe accounts for a relatively large share,ranging from 21.87%to 30.82%.The percentage of individual Pyr,Flu,were all around8%-15%,and the remaining individual PAHs accounted for a relatively small percentage.Different years or ratios can have a large impact on the percentage of individual Chry,Pyr and Fluo.（6）The carcinogenic toxicity equivalent dose BEQ values for mosquito coils releasing solid phase(PM_1.0)PAHs from combustion ranged from 0.074 to 38.449 ng/g·incense,and mutagenic equivalent dose MEQ values ranged from 0.034 to 50.473 ng/g·incense.The BEQ and MEQ values of smokeless mosquito coils were higher than those of smokeless coils.Mixed base class is higher than the toner class,wood powder-based mosquito coils are the smallest.The disk type is higher than the wire type.Among them,the BEQ and MEQ values of micro-smoked wood powder disc incense were the smallest.（7）The contribution of BaP released from mosquito coils to the carcinogenic equivalent dose BEQ and mutagenic equivalent dose MEQ ranged from 50.02%to 69.97%and 28.97%to 55.97%,respectively.The contribution of Bbf to BEQ and MEQ ranged from 11.67%to51.83%and 24.85%to 75.20%,respectively.Five-ring PAHs are the PAHs with the greatest effect on carcinogenic and mutagenic toxicity.（8）The carcinogenic toxicity equivalent dose BEQ values for the release of solid-phase（PM1.0）PAHs from the combustion of moxa strips ranged from 2.098 to 15.287 ng/g·moxa,and the mutagenic equivalent dose MEQ values ranged from 2.427 to 17.072 ng/g·moxa.The BEQ and MEQ values were larger for moxa with a smaller storage year or processing percentage.The BEQ and MEQ values were greater for the moxa with a smaller percentage of processing in the same storage year and for the moxa with a smaller percentage of processing in the same storage year.（9）The contribution of BaP released from moxa strips to the carcinogenic equivalent dose BEQ and mutagenic equivalent dose MEQ ranged from 71.78%to 74.42%and 62.03%to 66.06%,respectively.The contribution of Bbf to the BEQ and MEQ was around 5%to15%.The contributions of the remaining individual PAHs to BEQ and MEQ were mostly below 10%.Five-ring PAHs are the PAHs that contribute most to carcinogenic and mutagenic toxicity.It is recommended to use slightly smoky wood powder type disc incense and moxa with a larger percentage of processing or a larger storage year.