Indoor air quality in classrooms of primary and secondary schools during autumn and winter in Hangzhou

Abstract

Objective To understand indoor air quality in middle and primary schools of Hangzhou in autumn and winter seasons, and to provide references of promoting indoor air quality of schools.

Methods Totally 33 classrooms of 11 schools in urban area were selected into study during Sept.2018 to Jan.2019. Daily measurements of PM2.5 and CO ₂ were performed in selected classes during school working time by air quality monitors. Totally, monitoring data of 35 964 hours were analyzed using univariate and multiplicity analysis for PM2.5 and CO ₂ level, variability and possible influence factors.

Results In autumn and winter, hourly average values of classroom PM2.5 and CO ₂ concentration level in Hangzhou were between 35.30 to 74.65 μg/m ³ and between 949.17 to 2 029.98 mg/m ³, respectively. The concentration levels of PM2.5 and CO ₂ were higher with the temperature ( F = 1 412.84, 775.66, P<0.01). No statistical significance was be found for the difference of PM2.5 concentration among monitoring times. Wave changes in CO ₂ were observed with time variation PM2.5 and CO ₂ concentration level of 68.42% monitoring times was complied with standards. School type and temperature correlated with PM2.5 concentration level. The PM2.5 concentration level in senior high school was higher than that in junior high school, while the value in primary school was the minimum ( β = 0.44, P < 0.01). And the PM2.5 concentration increased with the temperature decreased ( β = 8.31, P<0.01). School type, temperature and monitoring time correlated with CO ₂ concentration level. CO ₂ concentration increased with the increase of grade, decrease in temperature and later time during the day ( β = 213.64, 162.38, P<0.01). The CO ₂ concentration level in later monitoring time was lower than that in earlier monitoring time ( β = -16.28, P<0.01).

Conclusion Classroom CO ₂ concentration level in Hangzhou was closed to that in European schools, while PM2.5 concentration level was much higher. Comparing with other cities in China, classroom PM2.5 and CO ₂ concentration level in Hangzhou is better. The results highlighted that school location, design and routine management should be advanced consideration for good air quality in classroom.

Abstract

【摘要】 目的 了解杭州市中小学校秋冬季节教室室内空气质量状况, 为提升教室空气质量提供参考。 方法 于 2018年9月至2019年1月, 选取杭州市区11所中小学校33间教室作为研究对象, 利用空气质量检测仪对正常使用时段 教室空气进行检测, 对收集的PM2.5和CO ₂数据进行分析。 结果 秋冬季节杭州中小学校教室PM2.5和CO ₂平均质量体 积浓度分别介于35.30~74.65 μg/m ³ 和 949.17 ~ 2 029.98 mg/m ³ 之间, 且均随寒冷程度增加而逐月增高 ( F值分别为 1 412.84, 775.66, P 值均<0.01)。PM2.5质量体积浓度不同时段之间的差异无统计学意义, CO ₂质量体积浓度随时段变化 呈现明显的波峰变化。在测量时段中, 68.42%的监测时段教室PM2.5和CO ₂质量体积浓度符合标准。PM2.5水平与学校 类型、寒冷程度有关, 年级越高、寒冷程度越高, PM2.5水平越高( β 值分别为0.44, 8.31, P 值均<0.05) ； CO ₂质量体积浓度 与学校类型、寒冷程度及时段有关, 年级越高, 寒冷程度越高, CO ₂水平越高；时段越晚, CO ₂水平越低( β值分别为 213.64, 162.38, -16.28, P 值均<0.01)。 结论 杭州市中小学校教室CO ₂质量体积浓度与欧洲中小学接近, 但PM2.5质量体积浓 度远高于国外;PM2.5和CO ₂质量体积浓度均较国内其他城市中小学略低。在学校选址、规划设计、日常使用管理等方面 应预先进行考虑以维持良好的教室室内空气质量。