title: Inactivation of Mold Spores from Moist Carpet Using Steam Vapor: Contact Time and Temperature.
abstract: Steam vapor has been shown to reduce viable mold spores in carpet, but the minimal effective temperature and contact time has not been established. This study evaluated the effectiveness of steam vapor in reducing the number of viable mold spores in carpet as a function of temperature and contact time. Seventy carpet samples were inoculated with a liquid suspension of Cladosporium sphaerospermum and incubated over a water-saturated foam carpet pad for 24 hr. Steam was applied to the samples as the temperature was measured from the carpet backing. Contact time was closely monitored over seven time intervals: 0, 2, 4, 8, 12, 16, and 20 sec. Following steam vapor treatment, mold spores were extracted from the carpet samples and the extract was plated on DG-18 plates at 1:1, 1:10, 1:100 dilutions followed by one week of incubation. Raw colony forming units were determined using an automated colony counter and adjusted based on dilution factor, extraction volume, and plated volume. Analysis of variance and linear regression were used to test for statistically significant relationships. Steam contact time exhibited a linear relationship to observed temperature of carpet backing (F = 90.176, R(2) = 0.609). Observed temperature of carpet backing had a positive relationship to percent reduction of mold (F = 76.605, R(2) = 0.569). Twelve seconds of steam vapor contact time was needed to achieve over 90% mold reduction on moist carpet.
authors.affiliation: a Saint Louis University College for Public Health and Social Justice, Department of Environmental and Occupational Health , St. Louis , Missouri.
authors.forename: Kee-Hean
authors.initials: KH
authors.lastname: Ong
authors.forename: Brett
authors.initials: B
authors.lastname: Emo
authors.forename: Roger D
authors.initials: RD
authors.lastname: Lewis
authors.forename: Jason
authors.initials: J
authors.lastname: Kennedy
authors.forename: Laxmi N A
authors.initials: LN
authors.lastname: Thummalakunta
authors.forename: Michael
authors.initials: M
authors.lastname: Elliott
mesh_terms: D002963:Cladosporium / Q000254:growth & development*; D015169:Colony Count, Microbial; D004203:Disinfection / Q000379:methods; D005430:Floors and Floorcoverings; D006796:Household Work / Q000379:methods*; D013172:Spores, Fungal / Q000254:growth & development; D013227:Steam; D013696:Temperature; D013997:Time Factors
chemical_list: D013227:Steam
keywords: carpet; mold/fungi; spores; steam cleaning