Mold Management of Wetted Carpet

Abstract

This study evaluated the growth and removal of fungi on wetted carpet using newly designed technologies that rely on physical principles of steam, heat, and fluid flow. Sixty samples of carpet were embedded with heat-treated house dust, followed by embedding, wearing with a hexapod, and wetting. Samples were inoculated using a liquid suspension of Cladosporium sphaerospermum prior to placement over a water-saturated foam pad. Incubation times were 24 hr, 7 days, and 30 days. Cleaning was performed using three methods; high-flow hot water extraction, hot water and detergent, and steam. Fungal loading increased from approximately 1500 colony forming units per area (CFU/cm²) in 24 hr to a maximum of approximately 10,200 CFU/cm² after 7 days with a slight decline to 9700 CFU/cm² after 30 days incubation. Statistically significant differences were found among all three methods for removal of fungi for all three time periods (p < 0.05). Steam-vapor was significantly better than the alternative methods (p <0.001) with over 99% efficiency in mold spore decline from wetted carpet after 24 hr and 30 days, and over 92% efficiency after 7 days. The alternative methods exhibited lower efficiencies with a decline over time, from a maximum of 82% and 81% at 24 hr down to 60% and 43% at 30 days for detergent-hot water and high-flow, hot water extraction, respectively. The net effect of the mold management study demonstrates that while steam has a consistent fungal removal rate, the detergent and high-flow, hot water methods decline in efficiency with increasing incubation time.

Keywords:

• steam cleaning
• carpet
• mold/fungi
• detergent
• high-flow hot water
• remediation

ACKNOWLEDGMENTS

We acknowledge Rick Hoverson (Advanced Vapor Technologies, LLC) for contributing the steam vapor machine, and Mike Downey (Steamin Demon Company) for loaning the high-flow hot water extractor carpet cleaning machine. The Carpet and Rug Institute provided funding for this project. This study does not endorse the specific manufacturer devices that were used.