In this study the health effects of moisture and micro-organisms among children attending a water-damaged school (School E) were studied comparing symptoms and diseases with schoolchildren attending a school with no water-damage (School C). A follow-up questionnaire study was made at the end of the next semester. The renovation was done during the previous summer. To validate the information of questionnaire comparison with children’s patients record child by child was examined. Water damage was discovered in a school building for primary school children in early 90-ties. The staff of the school had an excess of sickness absences and visits to a physician because of respiratory infections and symptoms. The first signs of water damage and mould were found in 1993. The visible damage was repaired in the next year. In May 1995, a technical investigation of constructions revealed wide spread moisture damage in the school building. Altogether 397 children at the age of 7-12 year attended the water-damaged school, 92% (n=365) out of them took part in the first part of this study. The longest time of exposure was 6 years among the children in the 6th grade an one year among children who finished the first grade in may 1995. The control group of this cross sectional study included 175 schoolchildren (92%) at the same age attending a school (School C) in the same suburban district. The control school was examined for this study and no water damage was found.
The renovation of the damaged school was ready at the beginning of November 1995. During the renovation procedures, the area of construction was well isolated. A questionnaire was sent to the parents of the schoolchildren concerning children’s health outcomes during the school year 1994-1995. The main emphasis was on respiratory symptoms and diseases. In addition, atopic diseases and the time of diagnoses were inquired. A one-year follow up study was carried out among these children from both schools. The second questionnaire for the follow-up was sent to parents in fall 1996 concerning spring semester 1996. Because of a wide spread of inflammatory diseases in autumn all around Finland, we did not include fall semester 1995 to the second questionnaire.
All medical records of the children from both schools who took part of this study were examined on respiratory infections, atopy and use of antibiotics. The blood samples were drawn from randomly selected children from both schools (study groups). IgE antibodies to a mixture of 10 common environmental allergens were determined with a multi-RAST® screening test, the Phadiatop RAST®. IgG antibodies to nine microorganisms most commonly indicating water damage were analyzed by enzyme-linked immunosorbent assay (ELISA).
In a cross-sectional study the incidence of common cold, respiratory symptoms and visits to a physician were significantly higher among children attending the water-damaged school. Although the incidence of respiratory infections tended to be higher also in school year 1995-1996, after the renovation of the school building, no significant differences remained, except for the visits to a physician according to the questionnaire. The elevated IgE values among the study group indicated a possible relationship between exposure and sensitization to common environmental allergens, including micro-organisms. The occurrences of new allergic diseases after the children started the school were commoner among the exposed children, especially among those with heaviest exposure.
The mean number of positive IgG findings was significantly higher among the exposed children. The number of positive IgG antibodies did not correlate with respiratory illnesses or symptoms at the individual level, even though the exposed children who had positive IgG antibodies to four or more microorganisms in the total group comparison tended to have higher respiratory morbidity. In the exposed group, a negative correlation was found between the number of positive IgG antibodies and the total value of allergen-specific IgE antibodies.
In order to validate the given information of parents about their children’s health in two consecutive years, patient’s records in a local health center were studied for comparison. Because over-reporting and under-reporting were about at the same level, the total number of ambulatory visits in the patients’ records and questionnaires seemed to indicate good reliability. More detailed individual investigation showed poor recall validity from the questionnaires, including a high percentage of unreported visits to the local health center from both schools. Use of antibiotics had a better recall than ambulatory visits to a physician.
The study indicates that information on health services in questionnaires is not reliable, at least when occurrences in a period of one year or more are evaluated. The use of patients’ records of the health center as a reference of accuracy is also unreliable, if the records of all health services available to the people in the community are not covered. In conclusion, respiratory symptoms and diseases and an increased risk to allergic diseases were found among children exposed to moulds in a school building.
Remediation of the building had a substantial effect to children’s respiratory health. Especially concerning atopy the long-term effects of those who had been exposed to micro-organisms for many years need more follow-up studies. According to our study IgG antibodies at the group level seem to be markers of exposure also among children.
