| Air pollution of particulate matter is one of the important factors leading to premature death,and its metal components can enter the human body with particulate matter.Because of their persistence and accumulation,particulate matter and heavy metals can produce teratogenic and carcinogenic effects on the human,which have been the subjects of study for many years.The exposure scenario of heavy metals in particulate matter is a determinant factor of the toxic effects of heavy metals and a crucial part of exposure assessment and health risk assessment.The traditional methods for exposure and health risk assessment are based on fixed surveillance,ignoring the differences of time-activity patterns of different populations,which makes the results uncertain.Therefore,based on the identification of typical exposure scenarios and investigation of exposure activity patterns,Baoding was selected as research site to discuss the concentration of different exposure scenarios and the individual exposure level of different populations,and carry out source appointment and analysis of influence factors.It may play a part in carrying out exposure evaluation and health risk assessment finely and accurately,providing theoretical support for individualized measures to control air pollution,offering a scientific basis for the public to make healthy travel,and ensuring the health and safety of the public.At first,on basis of investigation of exposure activity patterns,eight exposure scenarios were selected,such as residential scenarios,business scenarios,park,traffic scenarios,station,school,hospital and market.Besides,X-ray fluorescence spectroscopy was used to determine the concentration of heavy metals in Baoding during heating and non-heating periods.Based on the comprehension of the characteristics of metals pollution in atmospheric PM2.5,the source analysis and pollution level evaluation of different exposure scenarios were carried out.At the same time,based on the investigation of exposure behavior patterns of the population,the exposure levels and health risks of different populations exposed to metals in were explored,and some meaningful conclusions were obtained.Intelligent volume sampler?TH-150?and personal air sampler?BUCK LP-5?,energy dispersive X-ray fluorescence spectroscopy was used to determine the concentration of heavy metals in Baoding during heating and non-heating periods.At the same time,based on the investigation of time-activity patterns,the pollution characteristics,influencing factors,and exposure levels of heavy metals in individual PM2.5 were discussed.Finally,the health risk of heavy metals in the ambient particulate matter was evaluated and some meaningful conclusions were obtained.?1?There were differences in air-related exposure behavior patterns and exposure parameters among different sex,age and occupational groups in Baoding.The populations with high exposure levels from outdoor air pollution are mainly students,traffic police,couriers,drivers,farmers,vendors in Baoding City.The exposure factors are different,such as weight,height,inhalation rate,outdoor activity time,indoor activity time and travel time of different sex,age group and occupation group.?2?There were obvious seasonal differences of pollution levels of PM2.5 and its metals in Baoding.The concentrations of PM2.5 and its metals of non-heating period is lower than that of heating period.The concentration of PM2.5.5 during the heating period and non-heating period are 168.72?g/m3 and 83.55?g/m3,respectively.The concentration of Cd,Pb,As and Cr are 0.022±0.035?g/m3,0.143±0.081?g/m3,0.037±0.041?g/m3 and 0.048±0.060?g/m3 during heating period,respectively.The concentration of Cd,Pb,As and Cr are 0.003±0.006?g/m3,0.007±0.020?g/m3,0.033±0.020?g/m3 and 0.044±0.008?g/m3 during non-heating period,respectively.?3?The pollution levels of heavy metals in atmospheric particulate matter varied in different typical exposure scenarios.The station had the highest concentrations of PM2.5 which was 216.36?g/m3 while the hospital had the lowest concentrations of PM2.5.5 during heating period which was 145.43?g/m3.The business scenarios had the highest concentrations of PM2.5 which was 91.37?g/m3,while the park had the lowest concentrations of PM2.5 as 60.78?g/m3 during non-heating period.The station had the highest concentrations of metals which was 0.028?g/m30.100?g/m3,while the hospital had the lowest concentrations of metals which was 0.004?g/m30.036?g/m3during heating period.The traffic scenarios had the highest concentrations of metals while the park had the lowest concentrations of metals during non-heating period.The main sources of metals are natural sources,coal-fired sources,industrial sources and traffic emissions,which are basically the same in heating period and non-heating period.?4?Heavy metal elements of PM2.5 have certain potential health risks to the population in Baoding City,and there are seasonal,sex and occupational differences of the health risks.The non-carcinogenic risks and carcinogenic risk of metals in PM2.5are 0.003-1.99 and 2.09×10-6-1.57×10-3 in Baoding city,respectively.The non-carcinogenic risk and carcinogenic risk in heating period are bigger than non-heating period.The non-carcinogenic risk and carcinogenic risk of male are bigger than those of female.Primary school students have the highest health risk,while farmers have the lowest.Stations and markets have higher health risks while hospitals and parks have the lower.To sum up,metals in atmospheric PM2.5 existed contamination variously,and the pollution during heating period is particularly serious.The pollution levels of PM2.5 and its heavy metal?loid?s in station,traffic scenario and market are more serious,while those of the hospital and park are relatively slender.Heavy metal elements of PM2.5have certain potential health risks to the population in Baoding City.The health risks of station and market are higher than others while those of hospital and park are lower.Therefore,the use of pollutant monitoring techniques in different exposure scenarios for health risk assessment should be advocated,which can increase the accuracy and authenticity of health risk assessment. |
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