Personal Exposure Level And The Health Effects Of PM_2.5 And Black Carbon

The sources of atmospheric particulate matter(PM)are diverse,and the composition of PM is relatively complex.There are different individual exposure levels in different behavioral activities/microenvironments.Different components of PM also have different toxicities and human health effects.The mobile emissions has become the main source of air pollution in cities.Air pollutants emitted by transportation vehicles are complex mixtures.Black carbon(BC)as a pollutant marker of transport source emissions.Recently,many environmental health researches have focus on BC,but there are few studies on BC in China.Therefore,it is of great significance to study the exposure levels and health damage of PM2.5 and BC from different behavioral activities/microenvironments,especially the mobile traffic sources.Firstly,the contributions of 5 different behaviors/microenvironment(indoor eating,indoor sleeping,indoor general activities,outdoor and traffic)to the exposure concentration,dose,and intensity of individual PM2.5 and BC exposure in 51 volunteers were investigated to determine the main sources of individual PM exposure in Shanghai.Results show that the concentrations of individual PM2.5 and BC exposure in 5 different microenvironment/activities range from 3.0 μg/m3 to 574.0 μg/m3 and from N.D.μg/m3 to 21.8 μg/m3,respectively.Although individual exposure concentration of indoor regular activity was low,the highest daily inhalation dose of PM2.5(516.0 ± 153.5 μg/d)and BC(20.2 ± 8.9 μg/d)were obtained due to the high proportion of exposure time in indoor regular activity.The PM2.5 and BC exposure dose intensity in outdoor environment was the highest.In the traffic environment,the exposure intensity of BC was higher than that of PM2.5,however,in the other 4 microenvironment/behavior activities,it was converse.This result confirms that BC is an effective traffic emission marker.Secondly,the spatial and temporal distribution characteristics of individual PM2.5 and BC exposure were investigated in subway and private cars,which are typical public and private traffic tools in Shanghai,respectively.In addition,the differences between fixed and mobile BC monitoring were also analyzed.The results as following:(1)The morphology of particles collected in the subway station in Shanghai was irregular and diversified,including crystalline,spherical flocculation and columnar grain.The relative closed environment in the underground subway make the particles continuously accumulated.The daily average BC concentrations of the ground and underground line were 5.6 μg/m3 and 0.9 μg/m3,respectively.The concentration of BC on the platform(6.0～6.6 μg/m3)is 2 to 3 times that of the carriages(1.8～3.0 μLg/m3).The subway shield doors,rainfall and wind were helpful to reduce BC pollution.The daily BC expose dose of subway staffs as six times as that of the passengers.The source apportionment analysis shows that cooking and exhaust from the gasoline cars on ground might be primary sources of BC in subway stations in Shanghai.(2)There were significant spatial and temporal distribution differences of individual BC exposure levels monitored by mobile vehicle BC sampler.The individual BC exposure levels on outer ring road(13.5 μg/m3,IQR:9.2～20.0 μg/m3)were higher than that on middle ring road(5.1 μg/m3,IQR:2.5～0.4 μg/m3)and inner ring road(5.0 μg/m3,IQR:2.4～8.2 μg/m3)in Shanghai.BC pollution concentration during morning peak(14.4 μg/m3,IQR:6.5～22.4μg/m3)were higher than that during afternoon peak(7.5 μg/m3,IQR:3.8～13.3 μg/m3)by 35%.The average concentration of in-vehicle BC was around 56%higher during weekdays(14.1 μg/m3,IQR:7.5～22.4 μg/m3)than during weekends(5.9 μg/m3,IQR:2.6～10.1μg/m3).There were also spatial and temporal distribution differences of BC pollution levels in three fixed roadside monitoring sites.The in-vehicle-to-ambient concentration ratio(γ)=1.8 for the inner ring road at site A and γ =1.9 for the inner ring road at site B were obtained.This finding indicated that ambient BC measurements might not adequately represent personal exposure.Thirdly,Illumina RNA-seq technique and a new methylation beadchip method(Illumina 850K)were used to identify the cytotoxicity and genetic toxicity induced by PM2.5 and diesel emission particles(SRM2975)in vitro assay,respectively.In addition,the cytotoxicity,oxidative damage and inflammatory injury of biodiesel fuel combustion nascent particles R250 and oxide composite particles(O3-R250 and HNO3-R250)were explored.The results as following:(1)Compare with the control group,the survival rate of A549 cells significantly decreased(p<0.001)after exposure to PM2.5.A total of 712 differentially expressed genes were obtained from global transcriptome profiling.GO function enrichment analysis revealed that the biological processes of the immune system and responses to stress are major factors contributing to PM2.5-induced toxicity in A549.KEGG pathway analysis further proposes that infectious disease,cancers,cardiovascular disease,and immune disease pathway were the key human disease events that occur in A549 cells under PM2.5 stress.(2)The diameter of black carbon nascent particles model R250 used in this study is 30～60 nm.R250 consist of the amorphous corn and the outer graphited shell.Oxygen groups(C-O,C=O,O-C=O)were added into the R250 after the oxidation with HNO3 and 03.The cell activities of BEAS-2B cells were affected by all three particles.HNO3-8250 had the biggest effect,following by O3-R250 and R250,which induced cell activity significantly decrease only on the concentration higher than 50 μg/mL(P<0.05).The toxicity of three particles with the concentration higher than 12.5 μg/mL were significantly increased(P<0.05).Compare with the control group,the inflammation factors IL-6 expression in BEAS-2B treated with 12.5μg/mL R250,12.5 μg/mL HNO3-R250,and 25 pg/mL O3-R250 were highest,and reached up to 2.0,4.3 and 3.4 times.Compared with the primary particle R250,the 8-oxo-dG levels in cells exposed to O3-R250 significantly increased almost 3 times(P<0.05).However,HNO3-R250 did not significantly induce oxidative damage.(3)The diesel emission particle model SRM2975 used in this study is a disordered polycrystalline graphite nanoparticle.20μg/mL SRM2975 had significant proliferation inhibition effect on HUVEC cells(P<0.001).The apoptosis rate and DNA damage were significantly increased after exposure to 5～20μg/m3 SRM2975.The HUVECs showed a significantly incresed ROS after exposure to SRM2975 with a concentration of 0～20 μg/m3.149 significant differential methylated probes were enriched in 56 GO tenns and 107 KEGG signaling pathways.The majority of the enriched GO terms were related to calcium ion and heart muscle.The top three enriched pathways were ARVC,HCM and DCM.The individual PM2.5 and BC exposure characteristics were investigated in the traffic environment.The results preliminarily showed 1 that the cytotoxicity,health damage,related biological processes and gene signaling pathways of traffic PM.This study is helpful to further understand the toxicity mechanism of PM,and provides abeneficial experimental data for formulating solutions of protecting public health from PM.