The indoor environment in schools : Respiratory effects and air quality

Sammanfattning: The main objective of this work was to investigate relationships between the schoolenvironment and asthma and asthmatic symptoms in schoolchildren. Data on symptoms werecollected through postal questionnaires answered by 1,732 pupils in 39 randomly selectedschools, and were related to data on exposures obtained through hygienic measurements in theschools. Current asthma was more common in pupils attending a school with more openshelves in the classroom, more cat allergen in settled dust, and higher levels of formaldehyde,moulds and bacteria in the air. A follow-up study after 4 years showed that new onset ofasthma was more common in pupils who had attended a school with more settled dust, andmore cat allergen in the dust, and new pet allergy was related to higher concentrations ofrespirable dust. Among pupils without a history of atopy, new onset of asthma was morecommon in those who had attended a school with more formaldehyde or with a higherconcentration of total mould. In 1993, the Swedish ventilation standard was not reached in77 % of the investigated classrooms, and pupils attending schools where a new ventilationsystem was installed had a lower incidence of asthmatic symptoms compared to pupilsattending schools with no change of ventilation system. In a cross-sectional study amongschool employees it was found that half of the employees perceived the indoor air quality asbad, and this perception was related to higher concentrations of pollutants. The air exchangerate was the main predictor of the concentrations of pollutants in the school buildings. However, several of the pollutants that were important for asthmatic symptoms were alsorelated to characteristics of the classroom, such as fittings and furniture, and to the cleaningroutines. In conclusion, asthma and asthmatic symptoms in the pupils were related to factorsin the school environment. Settled dust, respirable dust, pet allergen, formaldehyde andmoulds were important. Several different measures should be undertaken when striving toreduce the concentrations in schools of pollutants with possible adverse health effects. Theventilation rate should be increased, the amount of fleecy or large-surface materials in theclassrooms minimised, and the cleaning of furniture and fabrics improved.