CONTROL OF EXPOSURE TO AIRBORNE VIABLE MICROORGANISMS DURING REMEDIATION OF MOLDY BUILDINGS - REPORT OF 3 CASE-STUDIES

Three different techniques for reducing exposure to microorganisms wer e tested during remediation of moldy buildings, concentrations of spor es (fungi and actinomycetes) were determined by filter sampling before , during, and after remediation. The local exhaust method used for asb estos dismantling was the most effective control method. In the constr uction zone, concentrations of microorganisms were 4-25 times higher d uring remediation than before it. In the adjacent area no increase in concentrations was seen. When the construction zone was placed under n egative pressure with a fan and isolated with a plastic barrier, conce ntrations of microorganisms were about 100 times higher there during r emediation work. Nevertheless, levels remained low in the adjacent are a. 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 migrati on of fungal spores from the construction zone to the adjacent area, a lthough it was less effective in prevention of actinomycete spore migr ation. it also decreased the levels of microorganisms in the construct ion zone below the preconstruction level within 2 hours. This study sh owed that levels of airborne microorganisms, including from the workin g area to adjacent area, can be reduced with commonly used dust contro l methods during demolition work. However, microorganism levels in the construction zone remained elevated. Therefore, personal protection o f construction workers is needed even with control techniques.