Air quality analysis of gymnasium in elementary and secondary schools in Yinchuan

Objective To investigate air quality of gymnasiums in elementary and secondary schools Yinchuan,and to provide the basis for better air quality improvement.Methods Twelve gymnasiums from elementary and secondary schools in Yinchuan were investigated,including CO2,formaldehyde,PM2.5,temperature and relative humidity according to national standards of Hygienic Standard for Gymnasium(GB 9668-1996).Results The density of CO2 in elementary and secondary schools gymnasiums before open hour was less than the national maximum level(0.15%).However,it showed higher than 0.15% 1h after open.The density of CO2 reached 0.25% in 16.7% secondary schools,66.7% higher of the national standard,while it reached to 0.21 mg/m3 in 16.7% elementary schools,75% higher of the national standard.The mean value of CO2 density 24 hours after open was higher than 0.15%.The density of the inhalable particle (PM2.5) before opening was less than national maximal standards (0.25 mg/m3),however,it increased to 0.62 mg/m3 an hour after opening in 16.7% secondary schools which was 148% higher of the national standard.Mean value of PM2.5 24 hours after opening was higher than 0.25 mg/m3.The temperature before and an hour after open in line with national lowest standard(16 ℃).The relative humidity before and after opening was slightly lower than national standard.Conclusion Air quality of gymnasiums in Yinchuan remains a concern in many elementary and secondary schools which needs further attention.