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ASSESSMENT OF FUNGAL (PENICILLIUM CHRYSOGENUM) GROWTH ON THREE HVAC DUCT MATERIALS
Chang*, J A., K. Foarde, AND D. VanOsdell. ASSESSMENT OF FUNGAL (PENICILLIUM CHRYSOGENUM) GROWTH ON THREE HVAC DUCT MATERIALS. ENVIRONMENT INTERNATIONAL 22(4):425-431, (1996).
Published Journal Article
The article discusses laboratory experiments to evaluate the susceptibility of three ventilation duct materials (fibrous glass ductboard, galvanized steel, and insulated flexible duct) to fungal (P. chrysogenum) growth. [NOTE: Many building investigators have documented fungal biocontamination in heating, ventilating, and air-conditioning (HVAC) ducts. It has been suggested that emissions of spores and volatile organic compounds from growing fungi may contribute to poor indoor air quality and result in adverse health affects.] Each sample was inoculated with spores of P. chrysogenum and incubated in a static chamber controlled at 97% relative humidity (RH) and 21 C for 6 weeks. Culturable spores on each sample were counted before and after incubation to determine the extent of fungal amplification. The results indicate that, of the newly purchased duct materials, no growth of P. chrysogenum was detected on the fibrous glass and galvanized steel, and only moderate fungal growth was detected on the flexible duct. The number of culturable spores on galvanized steel even decreased during the test period. Wetting the clean duct samples with sterile water did not increase amplification of P. chrysogenum over that seen without wetting. Soiling the samples with dust collected from residential HVAC systems enhanced the susceptibility of all three duct material to fungal growth, but at different levels of soiling. At a moderate soiling level (0.4-0.7 mg/cm2), growth occurred on the fibrous glass ductboard and the flexible duct, but not on the galvanized steel. At a markedly higher soiling level (9-18 mg/cm2), growth was seen on the galvanized steel as well. The results of these experiments suggest that dust accumulation and/or humidity should be properly controlled in any HVAC duct to prevent the growth of P. chrysogenum.
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