Analysis Of Health Risks Of Atmospheric Fine Particulate Matter And Its Potential To Induce Hydroxyl Radicals

At present,atmospheric particulate pollution in China is still serious,especially the fine particulate matter(PM_2.5,aerodynamic diameter less than 2.5μm).Long term PM_2.5 exposure will cause a series of health risks to residents.In this study,the PM_2.5 global exposure mortality model（GEMM）was used to estimate the relative risk of disease,premature death and life loss caused by long term PM_2.5 exposure in two typical cities of Jiangsu Province from 2015 to 2019.PM_2.5samples were also collected,and the oxidation potential of PM_2.5was detected with terephthalic acid（TA）.Due to the deficiency of TA detection method,a method for detecting hydroxyl radical by high performance liquid chromatography（HPLC）with salicylic acid（SA）was explored.The main results are as follows:（1）For the adults above 25 years old studied in Nanjing,the exposure risk of four diseases（COPD,LC,IHD and Str）decreased year by year（except 2018）.The relative risk of IHD and STR decreased with age.In the age group of 25-85,the number of premature death of men was higher than that of women,while in the age group of 85 and above,the number of premature death of women was higher.The annual total death caused by PM_2.5 was consistent with the annual trend of PM_2.5 concentration.In 2015,the annual averaged PM_2.5concentrations（55μg/m³）of Nanjing and Yangzhou were comparable,but the total number of deaths attributable to PM_2.5 exposure in Yangzhou（1498）was significantly higher than that in Nanjing（1024）,indicating that the health hazards of PM_2.5 were not only related to its mass concentration,but also related to its toxicity per unit mass.（2）Oxidative damage is the main mechanism of PM_2.5 endangering human health,and hydroxyl radical is the most important factor leading to oxidative damage.In order to further analyze the health hazards of PM_2.5,we collected PM_2.5 samples from Nanjing in 2015,Nanjing in 2017 and Yangzhou in 2015,and determined their hydroxyl radical content by TA method.Consistent with the results of health risk analysis,the concentration of hydroxyl radical in Yangzhou（66.11 ng/m³）was higher than that in Nanjing（45.62 ng/m³）in 2015.The higher oxidation potential of PM_2.5 in Yangzhou may cause a greater risk of death.In general,the concentration of hydroxyl radical increased with the concentration of PM_2.5,but the per unit mass PM_2.5concentration of hydroxyl radicals decreased with the concentration of PM_2.5.（3）Because TA determination method can neither quantify the consumption of reactants and the production of polyhydroxyterephthalic acid,nor exclude the interference of particles,we attempt to explore a HPLC detection method to accurately quantify hydroxyl radicals.Salicylic acid was used as the capture agent,and the gradient elution method was optimized:0-10 min（methanol:acetic acid water=4:6）,10-11 min（methanol:acetic acid water=6:4）,after 11 min（methanol:acetic acid water=6:4）.The flow rate was 1.0 m L/min and the detection wavelength was 254 nm.The resolution of SA and its two products was 4.54,the detection limit of products was below 0.5μg/m L,and the total detection time was 20 min.Comparing the two methods to detect PM_2.5 samples,it was found that there was a significant correlation between SA consumption and TA production（r=0.68）,but The advanced peak of needs to be further determined by analyzing a large numbers of PM_2.5 samples.