Slowly decreasing mucosal hyperreactivity years after working in a school with moisture problems.

In our first study in 1995, teachers, who had worked in a water-damaged school for more than 5 years, were tested for nasal histamine reactivity by rhinostereometry. They were found to have significantly increased reactivity compared with teachers in a school without these indoor-climate problems. This finding could not be explained by differences in atopy or other personal characteristics. In this 2-year follow-up study (1995-97), 26 of 28 teachers in the target school and all 18 teachers in the control school, who participated in the initial study, accepted to take part. They were tested with the same histamine provocation procedure and answered the same questionnaire as 2 years earlier. Technical measurements of temperature, relative humidity, dust, carbon dioxide, formaldehyde and total volatile organic compounds (TVOC) were carried out in both schools during the time period between the two test occasions. In this provocation test, the teachers from the repaired water-damaged school still demonstrated an increased reactivity to histamine compared with the teachers in the control school, but the difference between the growth curves of the provocation tests was less than in 1995. Teachers in the target school still complained about the indoor air quality more than their colleagues, although the complaints were less common. No major differences were observed in the technical investigation between the two schools and the measurements were all within values usually seen in schools in northern countries. Our conclusion is that the observed nasal mucosal hyperreactivity among the teachers in the renovated water-damaged school seems to persist over years and only slowly decrease even after successful remedial measures have been taken.