Particulate matter and carbon dioxide in classrooms – The impact of cleaning and ventilation

The objective of the study was to measure the indoor air quality in classrooms with special emphasis on particulate matter (PM 10) and carbon dioxide (CO2) and the impact of cleaning and ventilation.Material and methodPM 10 was analysed via gravimetric method and by laser beam technology. CO2 was analysed by infrared sensors. Measurements were collected for 3 weeks; first week: “normal” cleaning (twice a week) and ventilation; second week: intensified cleaning (five times a week); third week: intensified cleaning and intensified ventilation.ResultsLevels of PM 10 in the classrooms during the 3 weeks were 69±19 μg/m3 and they were dominated by occupancy and the persons’ activity. Intensified cleaning showed a significant decrease in all classrooms (79±22 to 64±15 μg/m3). The effect of ventilation on levels of PM10 was inconsistent – levels of CO2 were very high in all schools and could be diminished by intensified ventilation (mean 1459 to 1051 ppm).ConclusionAlthough further investigation is needed to study detailed characteristics of the PM 10 (size distribution, chemical identity) the data are sufficient to improve the cleaning and the ventilation in schools.