[Insufficient ventilation as the etiology of illness perception in an elementary school]

Two years after renovation of the classrooms in a primary school (installation of insulated windows and closing of the ventilation shaft) pupils and teachers complained about offensive odours, irritation of the eyes and of the nose, complaints of the respiratory tract, headaches and disturbed mental concentration. The presented study determines the causes, suggests measures for help and checks their effectiveness by means of measurements.

Before starting our measurements, the air quality had already been assessed by an expert. There was no evidence of elevated concentrations of air contaminants. Because of the content of phthalate plasticizers and flame retardants in the linoleum sealants there was an offensive odour. To determine the cause, the air in the subjective mostly affected classroom was analysed for phthalate plasticizers, their metabolites and alkyl phosphates. We also made aerosol measurements with a cascade impactor, determined bacterial counts in the air, and measured the indoor climate and the internal air flow.

The concentrations of phthalate plasticizers and their metabolites in the air were not elevated significantly. The screening for alkyl phosphates was negative. The amount of inhalable particles was 0.046 mg/m3. The bacterial count in the air was negligible. On the other hand the indoor climate during the heating period in winter was remarkably changed. The average room temperature was 26 degrees C (reaching a maximum of 36 degrees C with direct sunlight in the classroom), the average humidity was 21% (minimum 7%) and the change of air was approximately 0.5 per hour. Reopening the ventilation shaft and tilting of only one window resulted in a much greater rate of air change. After installation of temperature regulators and regular use of the venetian blinds in the classroom, the room temperature and the relative humidity during the morning lessons were, as a rule, normalised. Among both pupils and teachers the reports of offensive odours and health disorders were subsequently clearly reduced.

To determine the cause of health disorders indoors, it is apparently to be of great importance to carry out measurements of the climate as well as to assess the level of air contaminants. By use of modern energy-saving construction possible effects on the indoor climate should be be taken into account during the planning stage of changes to avoid health disorders resulting from changed interior climate conditions.