Study On Associations Between Elements In PM_2.5 And Children’s Health In Taiyuan Kindergartens

Taiyuan in Shanxi Province is of the most polluted cities in China Meanwhile,as a major coal production province,the main factor for the increase of atmospheric pollutant concentration is gas and dust generated from the process of coal collection and combustion.Although Taiyuan is less dependent on the coal industry than before,since it has special geographical and climatic characters,the air pollution situation is still worse and could cause serious health effect.In recent years,Taiyuan government has vigorously implemented a number of pollution prevention and control strategies,which have achieved remarkable outcomes.However,the concentration of atmospheric particulate is still in a high level.More and more people pay attention to the health effects of preschool children caused by particulate matter pollution,especially the potential source of elements.These elements can be adsorbed on the surface of particle,and enters the body through breathing that causing or aggravating respiratory disease of children.The prevalence of respiratory diseases,such as asthma in preschool children increases year by year.Therefore,study on the concentration,sources and health risks of particulate matter in the activity environment of preschool children can provide a scientific basis for the prevention and treatment of children’s respiratory diseases.In this study,ten kindergartens were randomly selected as in five administrative districts of Taiyuan.DustTrak TM DRX 8534 was used to measure the PM2.5 particulate matter concentration indoors and outdoors.Escort Elf pumps were used to collect air.GC-MS and ICP-MS were used to screen and analyze the elements in PM2.5 to determine the element type and concentration.At the same time,a questionnaire survey was conducted on all children(4,500)in 10 kindergartens,and an Exhaled NO detector(NIOX VERO)was used to test the exhaled NO value of children who stayed in the selected classroom that the particulate matter measurement were performed.A total of 507 children participate the exhaled NO test.Pearson correlation analysis and principal component analysis were used to determine the source of health-related metal elements in PM2.5.The health risk model was used to evaluate the non-cancer risk and cancer risk of different populations in the kindergarten.The effects of indoor and outdoor PM2.5 elements in the kindergarten on respiratory diseases such as asthma and allergic symptoms in preschool children was further analyzed,and finally we analyzed the association between the exhaled NO value in children’s breath and respiratory symptoms.The results showed that:(1)The average indoor PM2.5 concentration in the kindergarten during the study period was 0.27 ± 0.20 mg/m3,and the average outdoor concentration was 0.23 ± 0.20 mg/m3,which were higherthanthe second-level concentration threshold(7 5 μg/m3)of national air quality standard.(2)After screening and analysis,a total of 34 elements were screened out.The concentration of S element was the highest,with an average concentration of 29,112.58 ± 26,666.49ng/m3.The concentration of Cd,Pb,As,Mn,Ni,Cr,Co and Hg,the eight health-related element were 7.39± 4.73 ng/m3,620.22 ± 403.35 ng/m3,42.38 ± 30.06 ng/m3,340.14±256.22ng/m3,114.91± 109.84ng/m3,1002.34± 1128.73ng/m3,3.56± 2.93 ng/m3,2.84 ± 2.31 ng/m3,respectively,Among them,the concentration of Pb,Cd and As exceed the national standard concentration limit.(3)The results of Pearson correlation analysis and principal component analysis show that indoor and outdoor PM2.5 in kindergartens in Taiyuan may mainly come from coal combustion,metal smelting and transportation emissions.Mining and waste incineration also have a minor effect on PM2.5 concentrations in kindergartens.(4)The health risk assessment of PM2.5 element in kindergartens in Taiyuan show that Cr and Mn have a higher non-cancer risk(HQ>1).Boys are more at risk than girls,and children are more at risk than adults.For all people,the Cr,Ni,As,Cd,Co,and Hg elements that could enter the body through respiratory pathway have a cancer risk(Ri>10-6),and the cancer risk of Cr,As,and Ni is at a higher level(Ri>1O-4).(5)By comparing the non-cancer risk and cancer risk value of each element in PM2.5 in 2014 and 2004,the results show that Cr and Mn elements have non-cancer risk in both years,of which Cr increased by 6.56 times,and Mn Elements are slightly reduced.Cr,Ni,As,Cd,and Co have cancer risk in both years.Cr,Ni,and Co have an increased cancer risk.(6)The exhaled NO value of selected children was significantly positively associated with wheezing symptoms in the previous 12 months.The OR value was 1.11 and the 95%CI was 1.00-1.25.(7)The exhaled NO value was significantly positively related to elements other than Hg in the kindergarten,indicating that the measured elements,except for Hg can cause respiratory symptoms in children.(8)The geometric mean exhaled NO value of 507 children in the kindergarten was 10.0±5.2ppb,of which 10.6±5.8ppb for boys and 9.6±4.4ppb for girls.The highest value for boys is 36.0 ppb and the highest value for girls is 34.0 ppb.The results indicate that boys have higher exhaled NO value than girls,and to some extent boys may be more susceptible to respiratory diseases such as asthma.Overall,the results show that both indoor and outdoor elements from PM2.5 in kindergartens in Taiyuan City have different degrees of non-cancer risk and cancer risk to children.Moreover,an increase in element concentration will lead to an increase in exhaled NO value in children and increase the risk of children’s asthma disease.Therefore,effective measurements of elemental pollution prevention should be formulated to improve the living environment of preschool children.