过去教师们对上课时学生普遍出现嗜睡现象,百思不解。他们认为,我们学生的体质非常不错,学习也谈不上负担重、压力大,孩子们为什么会这样呢? 经北京市劳保所安全评价中心在与北大附中联手调查后发现:教室学生密集,每个学生占有空间过小,再加上教室往往长时间门窗紧闭,导致教室内空气质量下降。随着课时延长,室内二氧化碳含量会持续升高而缺氧,空气清洁度下降(在卫生学上,室内空气的清洁度一般是以二氧化碳的浓度为衡量指标),从而影 In the past, teachers were generally puzzled by the phenomenon of lethargy in students during class. They believe that our students’ physical constitution is very good, and that their studies are not burdensome and stressful. Why do children do this? The Beijing Center for Labor Safety Evaluation, together with the Peking University High School, found that students in the classroom are intensive. The small space occupied by the students, combined with the long hours of windows and doors in the classroom, caused the air quality in the classroom to decline. With the extension of class hours, the indoor carbon dioxide content will continue to rise and oxygen will be lacking, and the air cleanliness will be reduced (in terms of hygiene, the cleanness of indoor air is generally measured by the concentration of carbon dioxide).