Norbäck Dan, Nordström Klas
Department of Medical Sciences, Occupational and Environmental Medicine, Uppsala University, University Hospital, Uppsala, Sweden.
Int Arch Occup Environ Health. 2008 Oct;82(1):21-30. doi: 10.1007/s00420-008-0301-9. Epub 2008 Feb 2.
To study the effects of ventilation and temperature changes in computer classrooms on symptoms in students.
Technical university students participated in a blinded study. Two classrooms had higher air exchange (4.1-5.2 ac/h); two others had lower (2.3-2.6 ac/h) air exchange. After 1 week, ventilation conditions were interchanged between the rooms. The students reported symptoms during the last hour, on a seven-step rating scale. Room temperature, relative air humidity (RH) carbon dioxide (CO(2)), PM10 and ultra-fine particles (UFP) were measured simultaneously (1 h). Illumination, air velocity, operative temperature, supply air temperature, formaldehyde, NO(2) and O(3) were measured. Multiple logistic regression was applied in cross-sectional analysis of the first answer (N = 355). Those participating twice (N = 121) were analysed longitudinally.
Totally 31% were females, 2.9% smokers and 3.8% had asthma. Mean CO(2) was 993 ppm (674-1,450 ppm), temperature 22.7 degrees C (20-25 degrees C) and RH 24% (19-35%). Lower and higher air exchange rates corresponded to a personal outdoor airflow of 7 l/sp and 10-13 L/sP, respectively. Mean PM10 was 20 microg/m(3) at lower and 15 microg/m(3) at higher ventilation flow. Ocular, nasal and throat symptoms, breathlessness, headache and tiredness were significantly more common at higher CO(2) and temperature. After mutual adjustment, ocular (OR = 1.52 per 1 degrees C), nasal (OR = 1.62 per 1 degrees C) and throat symptoms (OR = 1.53 per 1 degrees C), headache (OR = 1.51 per 1 degrees C) and tiredness (OR = 1.54 per 1 degrees C) were significantly associated with temperature; headache was associated only with CO(2) (OR = 1.19 per 100 ppm CO(2)). Longitudinal analysis demonstrated that increased room temperature was related to tiredness (P < 0.05).
Computer classrooms may have CO(2) above 1,000 ppm and temperatures above 22 degrees C. Increased temperature and CO(2) may affect mucosal membrane symptoms, headaches and tiredness. Room temperature was most important. CO(2) associations may partly be temperature effects.
研究计算机教室通风和温度变化对学生症状的影响。
技术大学的学生参与了一项盲法研究。两间教室有较高的空气交换率（4.1 - 5.2次换气/小时）；另外两间教室的空气交换率较低（2.3 - 2.6次换气/小时）。1周后，各房间的通风条件进行了互换。学生们用七级评分量表报告最后一小时内的症状。同时测量室温、相对空气湿度（RH）、二氧化碳（CO₂）、PM10和超细颗粒物（UFP）（1小时）。测量了光照、风速、操作温度、送风温度、甲醛、二氧化氮（NO₂）和臭氧（O₃）。对第一个答案进行横断面分析时应用了多元逻辑回归（N = 355）。对参与两次的学生（N = 121）进行了纵向分析。
共有31%为女性，2.9%为吸烟者，3.8%患有哮喘。平均CO₂为993 ppm（674 - 1450 ppm），温度为22.7℃（20 - 25℃），相对湿度为24%（19 - 35%）。较低和较高的空气交换率分别对应每人7升/秒和10 - 13升/秒的室外气流。较低通风流量时平均PM10为20微克/立方米，较高通风流量时为15微克/立方米。在较高的CO₂和温度下，眼部、鼻部和咽喉部症状、呼吸急促、头痛和疲劳明显更为常见。相互调整后，眼部症状（每升高1℃，OR = 1.52）、鼻部症状（每升高1℃，OR = 1.62）、咽喉部症状（每升高1℃，OR = 1.53）、头痛（每升高1℃，OR = 1.51）和疲劳（每升高1℃，OR = 1.54）与温度显著相关；头痛仅与CO₂相关（每100 ppm CO₂，OR = 1.19）。纵向分析表明，室温升高与疲劳有关（P < 0.05）。
计算机教室的CO₂可能高于1000 ppm，温度高于22℃。温度和CO₂升高可能会影响黏膜症状、头痛和疲劳。室温最为重要。CO₂的相关性可能部分是温度效应。
