Comparison of indoor fungal spore levels before and after professional home remediation

Abstract

BACKGROUND: Methods for assessing and controlling fungi in the indoor environment have been well documented, but the role of fungal allergen avoidance and respiratory disease control is just beginning to be studied. OBJECTIVE: To investigate indoor fungal spore levels to determine if remediation produced reduction of these levels. METHODS: The study was performed on homes remediated for excessive fungal load during 2000 to 2002. Homes were included in the study if they had professional fungal remediation. Airborne spore samples were taken both before and after remediation. Slides were mounted with glycerin jelly that contained Calberla's solution. Spores were identified and counted microscopically at a magnification of X 1000. Counts were represented as the number of spores per cubic meter of air. RESULTS: Preevaluations and postevaluations were conducted for 17 structures. There were 92 individual collections before remediation and 99 collections after remediation. Mean counts were 131,687 (median, 9461) before remediation and 1291 (median, 409) after remediation. Aspergillus and Penicillium spores (which were counted together) occurred with the highest frequency in preremediation structures (88%). Stachybotrys spores were present in 53% of structures before remediation. Cladosporium spores were found in highest frequency in postremediation collections. Preremediation houses contained at least a 1-log increase in AspergilluslPenicillium spores over outside collections. In postremediation houses, indoor spore counts averaged 18% of outdoor counts. CONCLUSIONS: Remediation for indoor fungal spore contamination can significantly reduce spore counts. Indoor collections in preremediation buildings are generally much higher than outdoor counts for critical spore types, including Aspergillus/Penicillium and Stachybotrys. Remediation provides indoor spore levels substantially lower than outdoor counts.