Effects Of Air Pollution And Physical Activity On Cardiopulmonary Function Of Children In Beijing

The isolated impact of air pollution（adverse）and physical activity（positive）on children’s cardiopulmonary function have been well documented.However,the combination effects of air pollution and physical activity on cardiopulmonary function are not clear.Limited research has been conducted among adults in Europe,but the results across studies are not consistent.Given that children’s body shape and physical function differ significantly from adults,this issue needs to be further examined in children.Therefore,the purpose of this study was to examine the isolate and combination effects of air pollution and physical activity on cardiopulmonary function of children in Beijing.Based on the air quality data reported by the Beijing Environmental Protection Bureau,areas of lighter and heavier air pollution in Beijing were identified.Two administrative districts were selected from each area,with Yan Qing and Mi Yun identified as districts of lighter air pollution,and Tong Zhou and Da Xing as districts of heavier air pollution.One primary school was randomly recruited from each district,and around 100 students in grade 4⁶ were recruited for each school.The final sample consisted of 408 students（boys=217,girls=191;mean age=11.12±0.94 years）.Children’s daily physical activity time was reported by parents.Based on the quartile of physical activity time,children were classified as one of the four physical activity levels,i.e.,low,medium,high,and very high.Rest heart rate,systolic blood pressure,and diastolic blood pressure were measured using an electronic sphygmomanometer as indicators of cardiac function.Pulmonary functions,including forced vital capacity（FVC）,fastest expiratory volume in 1 second（FEV1）,and 1second rate（FEV1%）,respiratory peak flow rate（PEF）,were tested using a pulmonary function meter.Children’s maximum oxygen uptake(VO_2max)was measured by Progressive Aerobic Cardiovascular Endurance Run test（PACER）test.Differences of cardiopulmonary function between air pollution areas and across physical activity levels were examined by analysis of covariance（ANCOVA）.Two-way ANCOVA（air pollution*physical activity）was conducted to determine the combination effects of air pollution and physical activity on children’s cardiopulmonary function.If interactions of air pollution and physical activity were identified,analysis of variance（ANOVA）and independent sample T test were performed to examined the differences of cardiopulmonary function across physical activity levels and between air pollution areas with the other factor constrained,respectively.The results showed that boys in lighter air pollution area have higher FVC than those in heavier air pollution area（2.36±0.49L vs.2.23±0.47L,P<0.05）;VO_2max of girls in heavier air pollution area is higher than those in lighter air pollution area（45.79±2.70mL/kg/min vs.44.84±3.37mL/kg/min,P<0.05）.There are significant differences in diastolic blood pressure among girls with different physical activity levels（F（1,178）=4.23,P=0.006,η²=0.06）,namely girls with low physical activity level had higher resting diastolic blood pressure than girls with high physical activity level（65.80±8.40mmHg vs.58.41±7.53mmHg,P<0.05）.Significant interactions of air pollution and physical activity were found in boys for FVC（F（1,188）=3.03,P=0.03,η²=0.04）,FEV1（F（1,188）=4.94,P=0.003,η²=0.07）,FEV1%（F（1,188））=3.35,P=0.02,η²=0.05),and PEF（F（1,188）=3.50,P=0.01,η²=0.05）.Within the medium physical activity level,FEV1（2.03±0.46L vs.1.69±0.61L,P<0.05）,FEV1%（89.86±11.94 vs.76.22±19.98,P<0.05）and PEF（3.46±1.01L vs.2.59±1.20L,P<0.05）of boys in heavier air pollution area are higher than those in lighter air pollution area.Within the heavier air pollution area,FEV1 of boys of medium physical activity level（2.03±0.46L）is higher than those of low（1.72±0.46L）and high physical activity levels（1.77±0.51L,all P<0.05）;whereas PEF of boys of medium physical activity level is higher than all other physical activity levels（medium physical activity level PEF=3.46±1.01L,low physical activity level PEF=2.63±1.06L,high physical activity level PEF=2.68±1.18L,very high physical activity level PEF=2.82±0.88L,all P<0.05）.Results of this study indicated that air pollution has adverse impact on boys’FVC and physical activity has positive impact on girls’rest diastolic blood pressure.Meanwhile,VO_2maxmax of girls in heavier air pollution area is higher than those in lighter air pollution area.Significant interaction effects were found for air pollution and physical activity on cardiopulmonary function in boys,whereas no interaction effects were detected in girls.Longitudinal investigations are needed to further examine the combination effects of air pollution and physical activity on children’s cardiopulmonary function.