The relationship between measured moisture conditions and fungal concentrations in water-damaged building materials.

We determined the moisture levels, relative humidity (RH) or moisture content (MC) of materials, and concentrations of culturable fungi, actinomycetes and total spores as well as a composition of fungal flora in 122 building material samples collected from 18 moisture problem buildings. The purpose of this work was to clarify if the is any correlation between the moisture parameters and microbial levels or generic composition depending on the type of materials and the time passed after a water damage. The results showed an agreement between the concentrations of total spores and culturable fungi for the wood, wood-based and gypsum board samples (r > 0.47). The concentrations of total spores and/or culturable fungi correlated with RH of materials particularly among the wood and insulation materials (r > 0.79), but not usually with MC (r < 0.45). For the samples collected from ongoing damage, there was a correlation between RH of materials and the concentrations of total spores and culturable fungi (r > 0.51), while such a relationship could not be observed for the samples taken from dry damage. A wide range of fungal species were found in the samples from ongoing damage, whereas Penicillia and in some cases yeasts dominated the fungal flora in the dry samples. This study indicates that fungal contamination can be evaluated on the basis of moisture measurements of constructions in ongoing damage, but the measurements are not solely adequate for estimation of possible microbial growth in dry damage.

Control of exposure to airborne viable microorganisms during remediation of moldy buildings; report of three case studies.

Three different techniques for reducing exposure to microorganisms were tested during remediation of moldy buildings. Concentrations of spores (fungi and actinomycetes) were determined by filter sampling before, during, and after remediation. The local exhaust method used for asbestos dismantling was the most effective control method. In the construction zone, concentrations of microorganisms were 4-25 times higher during remediation than before it. In the adjacent area no increase in concentrations was seen. When the construction zone was placed under negative pressure with a fan and isolated with a plastic barrier, concentrations of microorganisms were about 100 times higher there during remediation work. Nevertheless, levels remained low in the adjacent area. The use of a portable exhaust fan with a side-draft hood decreased concentrations of fungi to one-tenth compared with demolition without the control technology. Furthermore, this method prevented the migration of fungal spores from the construction zone to the adjacent area, although it was less effective in prevention of actinomycete spore migration. It also decreased the levels of microorganisms in the construction zone below the preconstruction level within 2 hours. This study showed that levels of airborne microorganisms, including from the working area to adjacent area, can be reduced with commonly used dust control methods during demolition work. However, microorganism levels in the construction zone remained elevated. Therefore, personal protection of construction workers is needed even with control techniques.

Exposure to airborne microbes during the repair of moldy buildings.

Concentrations of airborne microbes, studied during the repair of seven moldy buildings, showed that concentrations of airborne fungi increased during the repair work. This was especially true during the demolition of moldy building materials, even though the total dust levels remained low. Concentrations of viable fungi sampled with a six-stage cascade impactor were 10(3) - > 1.9 x 10(5) cfu/m3, and the total concentrations of fungal propagules, as determined by the Camnea method (i.e., air filtration method with epifluorescence microscopic counting of acridine-stained organisms) showed 10(5)-10(6) counts/m3 during the demolition. Penicillium was the main genus throughout. Concentrations of viable total bacteria also increased, but this change proved less noticeable than that of the fungi. However, rather high concentrations of viable actinomycetes up to 10(4) cfu/m3 were detected during the demolition. Results show that construction workers are exposed to high concentrations of microbes, perhaps causing health problems. Thus, personal protection of both the respiratory system and eyes is strongly recommended for workers as they repair moldy buildings. In addition, the repair room should be isolated from other areas to protect occupants or any other people present.