Effects Of PM_2.5 And Polycyclic Aromatic Hydrocarbons On The Fractional Exhaled Nitric Oxide In Healthy Young People

Objective:1.To understand the exposure levels of outdoor PM_2.5 and gaseous pollutants in the two campuses of Heping district and Baodi district in Tianjin during the experiment period from 2014 to 2018,analyze the concentrations of various PAHs components in PM_2.5 samples,and evaluate the variation trends of air pollutant concentrations over a4-year period.2.To comprehensively evaluate the effect of PM_2.5,its PAHs components and gaseous pollutants exposure on the level of the fractional exhaled nitric oxide in healthy adult college students,and explore the lagging effect of different air pollutants on respiratory health,so as to provide theoretical basis and data support for optimizing the direction of environmental governance and protecting the respiratory system health of the population.Methods:In this study,67 healthy adult college students were followed up for 16 times between 2014 and 2018 using the study design of panel.During the follow-up,biological sample collection,measurement of the fractional exhaled nitric oxide levels and other physical examinations were performed.For 7 consecutive days before each follow-up,PM_2.5 samples were collected from the outdoor air for 24 hours.Meanwhile,meteorological data were monitored and monitoring data of gaseous pollutants were collected.The air samples collected were used to measure the PM_2.5 concentration and analyze the concentration of PAHs component in PM_2.5 samples.In terms of statistical analysis and data processing,Shapiro-Wilk method was used to test the normality of the data.T test or Wilcoxon rank sum test were used to compare the two groups.One-way ANOVA or Kruskal-Wallis rank-sum test was used to compare multiple group data.Spearman rank correlation test was used to understand the correlation between pollutants.A linear mixed-effects model was used to assess the association between exposure to air pollutants and changes in Fe NO levels.The effects of other confounding factors and other pollutants on the results were evaluated by using the covariate adjustment model and the two-pollutant model,and the lagging effects of different pollutants were evaluated by using the lagging model.All statistical tests in this study were conducted by two sided tests,and p<0.05 was used as the standard for significance.All statistical tests were conducted by R software with version 3.6.3.Results:1.This study included 67 subjects,26 males and 41 females,with an average age of 18.4±0.8 years and an average BMI of 21.9±3.2 kg/m².A total of 734 data were collected for Fe NO index,with an average level of 13.0[10.0-17.0]ppb.2.During the study period,PM_2.5 concentration（24-hour mean）in the main campus of Heping district was 59.0[41.3-85.7]μg/m³,and the pollution level in autumn and winter was higher than that in spring and summer.The sum of 17 kinds of polycyclic aromatic hydrocarbons（ΣPAHs,24-hour mean）concentration is 22.2[13.369.2]ng/m³.During the 4 years of follow-up,the concentration ofΣPAHs decreased significantly,and the pollution level in autumn and winter was higher than that in spring and summer.The 24-hour average concentrations of CO,NO₂and SO₂ and the maximum 8-hour average concentrations of O₃ were 1.00[0.69-1.60]mg/m³,46.5[30.3-72.5]μg/m³,15.0[9.00-24.5]μg/m³ and 56.5[22.3-87.3]μg/m³,respectively.3.According to the linear mixed-effects model analysis,it was found that there was an association between the exposure of PM_2.5 and PAHs with Fe NO levels under certain lagging conditions.In the Lag3 and Lag 0-6,an increase in the 24-hour average PM_2.5 concentration of 45.9μg/m³ was associated with an increase in Fe NO of 4.24%（95%CI:2.02%,6.51%）and 4.66%（95%CI:0.31%,9.20%）,respectively.In the Lag3and Lag 0-5,an increase in the 24-hour averageΣPAHs concentration of 56.2 ng/m³was associated with an increase in Fe NO of 5.84%（95%CI:4.25%,7.46%）and 5.43%（95%CI:3.45%,7.46%）,respectively.An increase in CO、NO₂、SO₂和O₃concentration of 0.81mg/m³、35.8μg/m³、13.5μg/m³and 66.3μg/m³ was associated with an increase in Fe NO of 8.86%（95%CI:5.48%,12.36%）,18.90%（95%CI:13.24%,24.84%）,4.36%（95%CI:2.50%,6.25%）,-15.58%（95%CI:-10.61%,-20.27%）in the Lag1,Lag2,Lag3 and Lag0,and 14.11%（95%CI:8.33%,20.21%）,13.56%（95%CI:7.17%,20.32%）,6.67%（95%CI:4.37%,9.01%）,-17.26%（95%CI:-12.31%,-21.93%）in the Lag0-3,Lag0-6,Lag0-5 and Lag0-1.Conclusion:1.During the 4-year follow-up period from 2014 to 2018,there was no significant difference in the concentrations of PM_2.5,CO,NO₂ and O₃ in Heping district of Tianjin.The concentration of PM_2.5,PAHs component and SO₂ significantly decreased year by year.The concentration of PM_2.5,PAHs component,CO,NO₂,SO₂ and O₃ show seasonal changes.The concentration of O₃ show a trend of being greater in spring and summer than in autumn and winter,while the concentrations of other pollutants show a trend of being greater in autumn and winter than in spring and summer.In addition,the concentration of PM_2.5,Ba P and NO₂ still exceeded the requirements of“GB3095-2012”in many cases in the past four years,mainly in the autumn and winter.The air pollution control in autumn and winter still needs to be strengthened.2.The increased exposure concentrations of PM_2.5,PAHs components,CO,NO₂and SO₂ are all associated with the increased the level of Fe NO under certain lagging conditions.However,the increase of O₃ exposure concentration is associated with the decrease of the level of Fe NO under certain lagging conditions.