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Chlorine Dioxide: The Safest of all Decontaminating Agents

Chlorine Dioxide Gas has a discernible odor at safe levels, which means you'll be able to smell the gas before it reaches unsafe concentrations, allowing you time to shut down the system and address the situation safely. Other agents, such as Ethylene Oxide (EtO) and Vapor Phase Hydrogen Peroxide (VHP), cannot be smelled until you are exposed to extremely high concentrations. While all decontaminating agents are by nature dangerous, chlorine dioxide gas has many traits which make it the safest method available.

Safety Thresholds

  • 0.1 PPM 8-hr TWA
  • 0.3 PPM 15-min STEL
  • 0.1 PPM odor threshold - self alerting

Safety Facts

The table below highlights important safety differences between chlorine dioxide and hydrogen peroxide.

Chlorine dioxide Gas Vapor Phase Hydrogen Peroxide
8-hr TWA
(time weighted average)
0.1 ppm 1 ppm
Any sterilizer must be dangerous to be effective and both methods use concentrations much higher than 8-hr TWA level. Aeration to the 8-hr TWA is over 10 times quicker with chlorine dioxide than with hydrogen peroxide.
Odor Detection Yes, at 0.1 ppm No
The ability to smell CD at the 8-hr safety level allows the user to be aware of exposure while still at safe levels. VPHP cannot be smelled so users are only aware of exposure at higher concentrations when coughing and choking occurs.
Carcinogenicity IARC - NO
(confirmed animal carcinogen)
The American Conference of Governmental Industrial Hygienists (ACGIH) classifies hydrogen peroxide as a confirmed animal carcinogen.
Cycle Times
(2500 ft3 room)
3-4 hours 6-12 hours
Cycle times are shorter with CD gas due to its faster aeration time to safe levels. VPHP can take hours to aerate down to safe levels after a decontamination cycle.
Distributive Properties Great
(true gas)
(vapors condense)
Gas laws state that gasses, such as CD gas, naturally distribute to uniformly fill their container. Hydrogen peroxide is a liquid at room temperature and will start to condense at temperatures below 228 C.
Ability to Penetrate Water Yes No
CD gas can penetrate and dissolve in water, decontaminating the water itself as well as the surface beneath. Hydrogen peroxide dilutes and breaks down in water and does not retain its full sterilization capacity.
Equipment Location Outside Room Location depends on manufacturer
Keeping generation equipment outside of the room is the safest option, as equipment can be handled and shut down in case of emergency.
Aeration Time
(2500 ft3 room)
30-60 minutes Typically overnight
Aeration to the 8-hr TWA is over 10 times quicker with CD.
In case of emergency, aeration is initiated for both methods. The longer the aeration time is, the longer an area is exposed to dangerous levels and cannot be accessed. VPHP aeration times are lengthy because of absorption into materials and condensation on surfaces.