What Is Chlorine Dioxide (ClO2)?
ClO2 is a selective oxidizer that has been used in public water, food safety and biological cleanup for more than a century. When it is generated, applied and monitored by trained technicians, it is one of the most effective and best-studied tools available for whole-space odor and biological remediation.
Where ClO2 is used today
Post-anthrax building decontamination
ClO2 was used to decontaminate United States government buildings after the 2001 anthrax mailings, including the Hart Senate Office Building. It was chosen because it penetrates porous materials and inactivates biological contaminants.
COVID-19 era disinfection
During the pandemic, ClO2 was included on the EPA List N of disinfectants that meet the criteria for use against SARS-CoV-2 on hard, non-porous surfaces under registered product labels.
Municipal drinking water
Many United States cities use ClO2 as a primary disinfectant for drinking water because it controls taste and odor and does not form the same class of trihalomethane byproducts as chlorine alone. The EPA sets a maximum residual disinfectant level for it in finished water.
Wastewater treatment
ClO2 is used in wastewater and industrial process water to control odor compounds, sulfides and biofilms, and to disinfect effluent before discharge.
Meat, poultry and seafood processing
The FDA permits ClO2 in specific concentrations as a sanitizer on food-contact surfaces and for use in poultry chiller water and produce process water. It is a standard tool in modern food safety programs.
Fruit and vegetable washing
Commercial produce washes and packing houses use ClO2 to reduce microbial load on fresh fruits and vegetables. Application follows FDA 21 CFR guidance on maximum concentrations and rinse requirements.
Over 100 years of documented use
ClO2 was first used to treat drinking water at Niagara Falls, New York in 1944, and its chemistry and use pattern have been studied continuously for more than a century in water, industrial and public health settings.
Why it is safe when professionally applied
The safety of any oxidizer depends on concentration, exposure time and containment. Our technicians use controlled generation, calibrated monitoring, structured dwell time and full ventilation before re-entry. People, pets and plants are out of the treated space during dwell, and the space is aired to background levels before the home is cleared. That is why regulators allow ClO2 in occupied-building programs, food processing and drinking water when it is dosed and monitored correctly.
Sources and further reading
- United States Environmental Protection Agency, National Primary Drinking Water Regulations for chlorine dioxide.
- United States Environmental Protection Agency, List N: Disinfectants for use against SARS-CoV-2.
- United States Food and Drug Administration, 21 CFR 173.300 chlorine dioxide use in food and food-contact surfaces.
- Centers for Disease Control and Prevention, Anthrax remediation activities in United States Senate office buildings.
- World Health Organization, Guidelines for Drinking-water Quality, chapter on chlorine dioxide.
This page is educational and does not make medical or legal claims. Always follow product labels and local regulations.
How we use ClO2 in a home
Our Whole House Reset delivers a controlled ClO2 vapor treatment to every room, void and HVAC pathway. Prep, dwell, ventilation and verification are all documented in writing. See the Whole House Reset service page or read about why we do not use ozone.
Want a professional ClO2 treatment quote?
Honest inspection, written scope, fully guaranteed.
- 100% Satisfaction Guarantee
- Eco-friendly, non-toxic, pet and kid safe
- Same-day response on most requests