Incidence of asthma diagnosis and self-reported allergy in relation to the school environment--a four-year follow-up study in schoolchildren.

SETTING: In schools, the indoor air quality is often poor and there is growing concern about its impact on the pupils' health.
OBJECTIVE: To study the incidence of asthma diagnosis and self-reported allergy in schoolchildren in relation to the school environment.
DESIGN: Data on asthma and allergies were collected through a postal questionnaire answered in 1993 and 1997 by 1347 (78%) pupils (initially aged 7-13 years) in 39 randomly chosen schools. Indoor pollutants were measured in about 100 classrooms in 1993 and 1995. Relationships between indoor pollutants and incidence of asthma diagnosis and self-reported allergy were studied by multiple logistic regression, adjusting for age, sex, atopy and smoking.
RESULTS: The incidence of asthma diagnosis was higher in pupils attending schools with more settled dust and more cat allergen (Fel d 1) in this dust. Incidence of self-reported furry pet allergy was higher in schools with more respirable particles. Among children without a history of atopy, a new asthma diagnosis was more common at higher concentrations of formaldehyde and total moulds in the classroom air.
CONCLUSION: A school environment with more dust, cat allergen, formaldehyde and moulds may affect the incidence of asthma and sensitivity to furry pets in schoolchildren.