The Effect of Ozone on Common Environmental Fungi

William Korzun; Jeffery Hall; Ronald Sauer

doi:10.29074/ascls.21.2.107

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William Korzun, PhD DABCC MT(ASCP)⇑
1. is associate professor, Department of Clinical Laboratory Sciences, Virginia Commonwealth University, Richmond VA
Jeffery Hall, MS MT(ASCP)
1. is laboratory manager, Mary Washington Hospital, Fredricksburg VA
Ronald Sauer, MA CLS(NCA), SM(NRM), SM(ASCP)
1. is associate professor, Department of Clinical Laboratory Sciences, Virginia Commonwealth University, Richmond VA

Address for correspondence: William Korzun PhD DABCC MT(ASCP), associate professor, Department of Clinical Laboratory Sciences, 301 College Street, Virginia Commonwealth University, PO Box 980583, Richmond VA, 23298-0583. (804) 828-9469, (804) 828-1911 (fax). wjkorzun{at}vcu.edu.

Abstract

OBJECTIVE: To determine if gaseous ozone can effectively kill common environmental fungi.

DESIGN: This study was designed to test the null hypothesis that there is no significant difference in viability between fungal conidia treated with ozone and fungal conidia not treated with ozone. A single control group design was utilized.

SETTING: Academic research laboratory.

INTERVENTIONS: Freshly prepared suspensions of Cladosporium spp., Stachybotrys spp., and Aspergillus niger conidia were diluted and plated onto the surface of solid agar plates. The plates were exposed to room air or to different concentrations of ozone for up to four hours, as were uninoculated plates. All plates were then incubated at 25°C until quantitative colony counts could be performed.

MAIN OUTCOME MEASURE: The effect of ozone on fungal conidia viability was assessed by comparing quantitative colony counts from conidia exposed to ozone to quantitative colony counts from conidia exposed only to room air.

RESULTS: There was a significant (p < 0.05) decrease in viable conidia of all three fungi, at ozone concentrations of 5.0 – 12.8 parts per million, by four hours of exposure. However, in every case, some conidia remained viable even at the highest level of exposure.

CONCLUSIONS: These data suggest that ozone must be used in conjunction with other methods of remediation or for more prolonged exposure times in order to eliminate fungal contamination of buildings.

ABBREVIATIONS: BRI = Building Related Illness; ppm = parts per million; SBS = Sick Building Syndrome.