Building-related symptoms and molds: a two-step intervention study

Aims: To evaluate the relation between mold growth and symptoms in an intervention study design. Methods: The building was examined by a walk-through and microbiological testing from surfaces and ventilation canals before and after each of two steps of the renovation. The examination program for the 25 employees comprised questionnaire, clinical examination, 2-week peak-flow monitoring, and blood samples, and in six persons also a bronchial challenge. Results: Initially the building had severe moisture problems with growth of Trichoderma and Phoma as dominating microfungi. The total number of symptoms from a nine-item building-related symptom score was 66%, peak-flow variability was 20%. After the first renovation, no visible mold growth was seen, but samples showed that the building was still contaminated. Symptoms decreased to 33%. After further cleaning the mold levels decreased on surfaces, and the number of symptoms decreased to 4%. Mean peak-flow variability fell to 15%. Discussion: In a poorly maintained building with moisture problems and mold growth, the staff had a number of irritative and general symptoms. The first renovation eradicated most visible signs of molds and gave a decreased number of symptoms. The second renovation sufficiently cleaned the building, and the rate of symptoms and peak-flow variability fell to normal levels. A thorough cleaning after renovation seems necessary for the eradication of symptoms.