上海市冬季雾霾期两校小学生肺功能变化分析
Variations of Lung Functions among School Children of Two Shanghai Primary Schools in Winter Haze Period
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摘要:
目的 观察上海市冬季雾霾期大气污染状况及小学生肺功能的变化趋势。 方法 在上海市中心城区和郊区各选择一所小学(A校和B校),每所学校3~5年级各随机抽取一个班级学生为样本研究对象,共182名,于2013年12月测试其肺功能3次(每周1次,连续3周);另于次年6月测试第4次,以作为对照。同时收集2013年12月和2014年6月,A、B两校就近的环境监测国控点大气细颗粒物(PM2.5)、可吸入颗粒物(PM10)、二氧化硫(SO2)和二氧化氮(NO2)4种污染物的监测数据。采用两样本t检验和χ2检验比较组间差异,以一般线性模型(GLM)中重复测量方差分析的方法分析肺功能变化趋势。 结果 2013年12月两校所在监测点PM2.5、PM10和NO2平均浓度均超过GB 3095-2012《环境空气质量标准》二级标准,其中PM2.5超标严重;2014年6月4种污染物浓度已达到国家二级标准,且明显低于2013年12月(P < 0.01)。所调查的182人中,完成4次肺功能检查的有160人,占87.91%。两校学生性别、年龄、身高、体重差异无统计学意义;A校第2次用力肺活量(FVC)和第3次的呼气流量峰值(PEF)高于B校(P < 0.05);各肺功能指标均有随时间而变化的趋势(P < 0.05或P < 0.01),FVC值存在时间和学校中的交互作用(P < 0.01);FVC、第一秒用力呼气量(FEV1)、50%肺活量最大呼气流量(MEF50%)、25%肺活量最大呼气流量(MEF25%)4次检查结果均呈线性降低(P < 0.01);两校边际均值轮廓图显示,FVC、FEV1、MEF50%和MEF25% 4次结果呈降低趋势,PEF、75%肺活量最大呼气流量(MEF75%)和用力呼气中段流量(FEF25%~75%)则前3次依次降低,第4次回升;经检验,2013年12月各指标的边际轮廓均值与2014年6月明显不同(P < 0.01或P < 0.05)。 结论 2013年12月冬季雾霾期上海市两监测点空气质量较差,周边小学生肺功能大气道和小气道功能指标均逐渐降低,雾霾期后仅部分指标回升,个别指标仍未完全恢复。 Abstract:Objective To study air pollution and variations of lung functions among primary school children in haze period in winter in Shanghai. Methods A longitudinal survey of lung functions was conducted among 182 children cluster sampled in one class from each of grade 3-5 in two primary schools (A was located in downtown area and B was located in suburban area).Lung functions of the students were examined once a week for three times in December 2013 and once in June 2014 as control.Daily realtime monitoring data of fine particular matter (PM2.5),inhalable particular matter (PM10),sulfur dioxide (SO2),and nitric dioxide (NO2) in December 2013 and June 2014 at two national environmental monitoring spots close to the two schools were collected.Student's t test and chi-square test were used to analyse the difference between two groups.Variance analysis module for repeated measures of general linear model (GLM) was used to examine the trend of lung function indicators. Results The average PM2.5,PM10,and NO2 concentrations in December 2013 exceeded the national air pollution level Ⅱ stipulated by China Air Quality Standards (GB 3095-2012),especially PM2.5 which reached the severe pollution category.The four air pollutants' concentrations in June 2014 complied with the level Ⅱ and were much lower than those in December 2013(P < 0.01).There were 160 out of 182 children (87.91%) completed four lung function examinations,and the gender,age,height,and weight between the children of two schools appeared no differences.The forced vital capacity (FVC) at the second time and the peak expiratory flow (PEF) at the third time of examination for school A were higher than those for school B (P < 0.05).All lung function indicators showed a variation tendency over time (P < 0.05 or P < 0.01).An interaction effect between time and school was also observed on FVC (P < 0.01).The variation of FVC,forced expiratory volume in one second (FEV1),maximal expiratory flow at 50%(MEF50%),and maximal expiratory flow at 25%(MEF25%) showed a descending trend over the four examinations (P < 0.01).The marginal mean plots showed that FVC,FEV1,MEF50%,and MEF25% were reduced linearly over the four examinations;PEF,maximal expiratory flow at 75%(MEF75%),and forced expiratory flow between 25% and 75%(FEF25%-75%) went down in the first three examinations,but went upward in the fourth examination.The marginal means of lung function indicators in December 2013 were different significantly compared with the results of June 2014(P < 0.05 or P < 0.01). Conclusion The air pollution around the two schools was serious in December 2013 compared with June 2014,and the children in the two schools experienced gradually reduced big and small airway functions.Some indicators rebounded after the haze period,but some indicators maintained at low levels.
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