["Breathing freely" in schools--results and model approaches concerning the air quality in classrooms].
Seven schools in Lower Saxony participated in a scientific re-search project measuring the concentration of carbon dioxide (CO2), indoor air temperatures and the relative air humidity in naturally ventilated classrooms on 58 days during the period of one year. The results are as follows: The hygienic reference value of 1500 ppm CO2 (in accordance with the official German regulation DIN 1946-2) was exceeded on 7 days in summer when measurements were taken (32% of all samples in summer) and on 32 days in winter (89% of all samples in winter). The mean CO2-concentration was 1316 ppm, 766 ppm and 1652 ppm in all samples (58 measuring days), summer samples (22 measuring days) and winter samples (36 measuring days), respectively. The mean indoor air temperature was 21.7 degrees C, 22.9 degrees C and 20.9 degrees C. The mean relative humidity was 50.7%, 54.3% and 48.5%. The mean number of persons per classroom (including the teacher) was 25.1, corresponding to a mean volume of 8.5 m3 for each person and a mean area of 2.9 m2 per person. A statistical association of CO2 concentration with season, outdoor temperature and the age of the windows was found. A software programme has been developed for calculating the concentration of CO2 depending on the number of persons and the ventilation rate in a classroom. A 3-level scheme based on CO2 concentration was developed to assess the air quality. The results showed that the classrooms were not ventilated regularly but depending on the outdoor temperature and the season. Deficits concerning all 3 parameters were found. It is very likely that the deficits are not limited to the schools participating in this project. Ventilation and indoor climate deficits might cause health problems and therefore lead to costly measurement programmes. To enable schools to take their own health-related measurements, measuring instruments were purchased which can be loaned to schools in Lower Saxony.
Grams
H
H
Niedersächsisches Landesgesundheitsamt, Hannover. Herbert.Grams@nlga.niedersachsen.de
Hehl
O
O
Dreesman
J
J
D016902:Air Pollution, Indoor; D002245:Carbon Dioxide / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods; D005858:Germany; D006801:Humans; D006813:Humidity; D008834:Microclimate; D008962:Models, Theoretical; D011379:Prognosis; D012044:Regression Analysis; D012574:Schools; D012621:Seasons; D012984:Software; D013696:Temperature; D013997:Time Factors; D014691:Ventilation
D002245:Carbon Dioxide