Differences In Chemical Compositions And Cell Responses Of Inhalable Particles From Typical Biomass Combustion Emissions

Atmospheric inhalable particles are the main components of haze in China,and their chemical components and sources are complex,which have serious harm to human health.Among them,fine particulate matter(PM_2.5)pollution is a common environmental problem in the world and is particularly prominent in China.In addition to the well-known diseases such as respiratory system and cardiovascular system,it can also cause changes in immune func-tion and induce or aggravate allergic diseases such as asthma and allergic rhinitis.In order to explore the temporal and spatial differences of PM_2.5 sensitization and the effects of particu-late matter from different sources on cellular inflammation,PM_2.5 samples were collected from four regions of Nanjing,industrial,suburban and rural areas throughout the year.The in vitro exposure test of rat basophils（RBL-2H3）was carried out to determine the cell survival rate,the release ofβ-hexosaminidase and histamine and the expression of related proinflam-matory factors in each experimental group.According to the analysis results of particulate matter source released by environmental protection bureaus in major cities,it can be seen that the contribution of biomass combustion source can not be ignored.Considering that biomass combustion is one of the important sources of air pollution in China and the impact of partic-ulate matter on cell inflammation,10 typical biomass combustion samples in Nanjing were selected to simulate stove combustion in the laboratory.Inhalable particles with different par-ticle sizes(PM_2.5 and PM₁₀)were collected by dilution channel sampling method,and their carbon components,metal elements and water-soluble components were determined.Human lung epithelial cells（A549）were exposed to biomass combustion in vitro.The toxic effects of particulate matter emitted from biomass combustion were evaluated from cell activity,in-flammatory damage and oxidative damage.The main results are as follows:（1）Urban-industrial winter,spring and suburban-rural autumn PM_2.5 has stronger sensi-tization.The sources of particulate matter in winter and spring are mostly human,which have strong pro-inflammatory.The particulate matters in winter and spring were largely due to an-thropogenic sources with the induction of strong pro-inflammatory effects.PM_2.5 concentra-tion was high in October and November,as well as in January and February of the following year,and was negatively correlated with wind speed and temperature.PM_2.5 in urban and in-dustrial areas in winter and spring and suburban and rural areas in autumn demonstrated the strongest degree of sensitization for a surrogate of mast cells（RBL-2H3 cells）under cell cul-ture conditions.According to the correlation analysis between chemical components and in-flammatory factors in PM_2.5,it can be seen that particulate matter in winter and spring mainly comes from anthropogenic sources and has a strong pro-inflammatory effect.Automobile ex-haust,industrial production,fossil fuels and biomass combustion have a great impact on the inflammatory response.Especially focusing on the correlation between water-soluble ion components and inflammatory factors,it can be seen that K⁺and Cl^-in PM_2.5 samples in rural and suburban areas are significantly positively correlated with inflammatory factors,which is speculated to be mainly due to cell inflammation caused by biomass combustion.（2）The chemical compositions of particles with different particle sizes produced by dif-ferent biomass combustion are significantly different.For carbon fractions,the OC/EC ratios of PM_2.5 and PM₁₀ produced by ten typical biomass combustion were between 0.53～11.77 and0.84～10.97,respectively.For water-soluble ions,K⁺and Cl^-are the main components of wa-ter-soluble ions in biomass combustion source particles.For metal elements,among the five major elements measured,Na and Ca in particulate matter account for a large proportion.Among the 12 heavy metals,Zn,Cr,Cu and Ni have higher contents.The chemical composi-tion of particulate matter emitted from different biomass combustion is also different.In addi-tion to corn cob,total carbon（TC）and water-soluble ions are the main particulate matter emitted from straw fuels,and the proportion of metal elements in particulate matter is small,accounting for only 1.20%～4.31%.TC is the main component of particulate matter emitted by fuelwood combustion.（3）Particles with different particle sizes emitted from different biomass combustion can cause different degrees of inflammatory damage and oxidative stress in cells.In addition to rape straw,the toxicity of fine particles produced by the same biomass combustion is stronger than that of coarse particles.The release levels of IL-6 in the supernatant of cells induced by PM₁₀ from biomass combustion sources were higher than those of PM_2.5,but the levels of TNF-αinduced by PM₁₀ from other biomass combustion sources were lower than those of PM_2.5 except peanut straw and sesame straw.PM_2.5 and PM₁₀ can induce oxidative stress in cells,and the level of ROS production is negatively correlated with the level of GSH-px pro-duction.In general,the level of oxidative stress induced by PM₁₀ is lower than that induced by PM_2.5.In summary,the pro-inflammatory effect of in vitro cells has a strong correlation with biomass combustion.Biomass combustion is one of the important sources of air pollution in China,and its contribution cannot be ignored.The chemical composition of particulates emit-ted from different types of biomass combustion is different,and the toxic effect on cells is also different.For the treatment of biomass combustion particulates,due to the high content of heavy metals（Zn,Cr,Cu,Ni,etc.）in the combustion particulates,it is necessary to treat them,collect flue gas,and explore and develop their sustainable utilization value,which can not only avoid waste of resources and alleviate environmental pressure,but also bring good economic and social benefits.