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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