Significance of indoor environment for the development of allergic symptoms in children followed up to 18 months of age.

The development of symptoms possibly related to allergy or other forms of hypersensitivity was studied in a group of 638 children on two occasions: when the children were 3 and 18 months of age. Standardized questions were used to collect basic information about the child, technical characteristics of the home, and the mother's perception of the indoor climate. All reported exposure factors were analyzed in relation to the child's symptoms at 18 months of age, by logistic regression techniques. A family history of atopy was associated with a high incidence of most of the investigated symptoms. Attendance at a day nursery before 18 months of age increased the risk of recurrent colds and the need for several courses of treatment with antibiotics. If the mother smoked, the children more often suffered from protracted coughing episodes. If the child has a sibling, the risk of developing a wheeze, repeated colds, and the need for antibiotic treatment increased. No building factors, such as size of the home, heating and ventilation system, type of foundation, dampness, or presence of wall-to-wall carpets, showed a significant correlation to symptoms reported in the children. However, if the mothers reported symptoms that are often connected with "sick buildings", the children more often had eczema, dry skin, or reactions to food. The mothers' complaints about indoor air quality and climate and mucous membrane symptoms were significantly related to the type of building and presence of condensation on the windows in winter, a finding which may indicate that indoor climate factors also have some effect on the health of the children. This study reports the prevalences of symptoms until the age of 18 months. At this age, the allergic manifestations are usually nonspecific, and follow-up examinations to 4-5 years of age are needed before any definite conclusions can be drawn about the development of atopic diseases due to indoor climate factors.