1. Makes Contact
ClO₂ reaches exposed microbial surfaces and reactive targets.
Independent science-based resource
The Power of
Chlorine Dioxide
Clear, source-backed information about chlorine dioxide chemistry, microbial control, mold research, odor applications, water treatment and established uses.
EXPLORE THE FACTSClO₂
Understanding ClO₂
What Is Chlorine Dioxide?
Chlorine dioxide (ClO₂) is a reactive oxidizing agent with chemistry distinct from chlorine bleach. Its properties have led to established uses in drinking-water treatment, industrial water systems and specialized microbial-control applications.
Performance depends on the organism, concentration, contact time, temperature, humidity, organic load and application method.
MICROBIAL SCIENCEThe science
How Chlorine Dioxide Works
Chlorine dioxide (ClO₂) is a selective oxidizing agent. The artwork below shows the four-stage oxidation concept from contact through microbial inactivation. Actual efficacy depends on organism, concentration, contact time and environmental conditions.
2. Selective Oxidation
Reactive chemistry modifies susceptible proteins and other biomolecules.
3. Disrupts Function
Oxidative damage can interfere with membrane integrity and critical biological processes.
4. Inactivation
When sufficient oxidative damage occurs, the microorganism can no longer maintain normal function or replication.
Mold remediation research
Chlorine Dioxide & Mold
EPA laboratory research evaluated ClO₂ fumigation against five molds on latex-painted and wallpapered gypsum wallboard, pine wood, ceiling tile, carpet and glass. The work measured viable mold as well as selected allergen and mycotoxin outcomes.
The EPA report also describes conventional remediation fundamentals: identify and correct moisture sources and remove waterlogged materials where appropriate. Chemical treatment is not a substitute for fixing the water problem.
WATER DAMAGE + MICROBIAL GROWTH
Stachybotrys chartarumCOMMONLY CALLED “BLACK MOLD”Included in the EPA building-material study.
Image: Dr. Sahay / Wikimedia Commons, CC BY-SA 3.0
Chaetomium globosumRESISTANT SPORE STRUCTURESelected because of resistance to adverse conditions.
Image: Wikimedia Commons; see source page for license
Aspergillus fumigatusINDOOR / ENVIRONMENTAL MOLDOne of five species evaluated by EPA.
Image: CDC / Dr. Libero Ajello, PHIL 4297
Aspergillus versicolorINDOOR MOLDEvaluated on representative building materials.
Image: Wikimedia Commons; see source page for license
Alternaria alternataDAMP-BUILDING MOLDViability and related allergen measurements were examined.
Image: Yulianna.x / Wikimedia Commons, CC BY-SA 4.0>4-log₁₀ reduction in the EPA study under its specified high-exposure condition
The report found greater than 4-log₁₀ reduction for the five tested species at 9000 ppmv-hour, 75°F and 75% RH on several tested materials. This is a controlled laboratory result, not a field-use recipe or universal performance guarantee.
Mold & biofilm control
ClO₂ vs. UV-C vs. Ozone
The comparison artwork below presents the different mechanisms, reach and practical limitations of these technologies, including biofilm and HVAC surface considerations.
About the field example:
The HVAC-media photographs in the comparison are user-supplied field images. They document visible contamination conditions. Because the facility's laboratory reports are not available for publication, the field event is presented as an application example rather than independently verified efficacy data.
Uses & applications
Where Chlorine Dioxide Is Studied & Used
Mold Remediation ResearchControlled research has evaluated ClO₂ against molds on water-damaged building materials.
Mold & Mildew OdorOxidizing chemistry can address certain odor-causing compounds; moisture sources still must be corrected.
Bacteria & MicrobesClO₂ has documented antimicrobial applications under specified conditions.
Facilities & EnvironmentsSpecialized decontamination applications have been documented.
Water TreatmentClO₂ is used in public-water treatment and other water applications.
Food & IndustryPermitted uses depend on the product, formulation, label and applicable regulation.
Research & studies
Read the Primary Sources
Laboratory Evaluation of ClO₂ Fumigation for Mold Remediation
EPA/600/R-13/229 evaluated five mold species on representative building materials.
VIEW EPA REPORT →Effect of Chlorine Dioxide Gas on Fungi and Mycotoxins
Peer-reviewed controlled fungal research examining susceptibility and treatment conditions.
READ STUDY →NIOSH Pocket Guide: Chlorine Dioxide
Occupational hazard information, physical properties and exposure limits.
VIEW NIOSH →Disinfectants for Biofilm & Legionella Control
A comparative model plumbing study found chlorine dioxide and chlorine among the most effective tested treatments, with ClO₂ showing longer residual activity.
READ STUDY →Ozone Antimicrobial Efficacy on Building Materials
EPA research found surface inactivation on building materials difficult even at relatively high ozone concentrations.
VIEW EPA REPORT →Safety
Research Results ≠ Field Instructions
Concentrations used in controlled research can be far above occupational exposure limits. Professional controls, monitoring, product labeling and applicable regulations matter.
0.1 ppmNIOSH recommended time-weighted average occupational exposure limit.
0.3 ppmNIOSH short-term exposure limit.
5 ppmNIOSH immediately dangerous to life or health (IDLH) value.