A case study on extensive fungal growth that occurred in an apartment building after firefighting efforts is described in this paper. Exposure to airborne microorganisms (both viable and total) was investigated by filter sampling in three periods before and during remedial actions after the fire. Material samples were also analyzed. Extensive mold growth was observed on the building materials as soon as eight days after the fire. High concentrations of fungal spores, 10(7) cfu/g, were found when material samples were analyzed. Concentrations of airborne fungal spores (10(4) spores/m3) were also high and increased by two orders of magnitude during the demolition of moldy building materials and during the clean-up after the demolition. The proportions of airborne viable fungi in comparison with the total spore concentrations were 28-83% immediately after the fire, but they had decreased to