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Method Comparisons

There are many considerations to make when trying to choose a decontamination agent. On this page and on the tabs to left we explore the different methods available for sterilizing and decontaminating and the advantages and limitations of each of these. There is also information below outlining the steps you must take in order to carry out a successful decontamination and the environmental factors you must consider when choosing a method. Chlorine dioxide, a true gas, offers many benefits over other decontaminating agents.

Sterilization with chlorine dioxide gas offers many benefits over other decontaminating agents.

Why Choose Chlorine Dioxide?

True gases such as chlorine dioxide (CD) and formaldehyde are the only truly effective agents for the decontamination of buildings, rooms, isolators, and biological safety cabinets as gases offer many benefits over other agents. In order for any decontaminating agent to be successful, three important Principles of Decontamination MUST be followed;

Principles of Effective Decontamination

Complete Distribution

For a true gas such as chlorine dioxide, its small molecular size (approximately 0.124 nm) and natural ability to fill any space it is injected into offers an unmatched distribution ability.

Total Penetration

Chlorine dioxide gas is a selective and highly effective oxidizer allowing it to easily penetrate surfaces, cracks and crevices and can even penetrate through organic matter.

Concentration and Contact Time

Chlorine dioxide is a colored gas and its concentration can be accurately measured and monitored in real-time allowing for tight control of important decontamination process parameters.

Chlorine dioxide's many unique features are what makes it a highly effective and efficient sterilizing agent. The process is easy to validate and is the best choice when considering a decontamination method. Chlorine dioxide has a small molecular size (approximately 0.124 nm) and a being a true gas has a natural ability to completely and evenly fill any space it is injected into giving it unmatched distribution abilities. It is also a selective and highly effective oxidizer allowing it to easily penetrate surfaces, including microscopic cracks and crevices and even has the ability to penetrate through organic matter. Chlorine dioxide is a colored gas and can be accurately measured and monitored in real time allowing for tight control of critical decontamination process parameters. Chlorine dioxide is also able to be quickly aerated as it will not condense on surfaces or absorb into many materials.

Unlike vaporous or liquid based decontamination agents, chlorine dioxide is unaffected by small temperature changes and will remain in the gaseous state over a wide range of temperatures and pressures. Gases are also unaffected by room configuration and equipment loading and positioning. Liquid agents, such as hydrogen peroxide, have a boiling point of 109°C (228°F) and will only exist in their vapor phase at or above this temperature. As most decontaminations take place at room temperature, approximately 21-22°C (70-718°F), these agents are sometimes referred to as lazy gases, meaning they will constantly be condensing back to their liquid form negatively affecting their distribution and penetration abilities.

Vapors are not Gases

Liquids and vapors, including hydrogen peroxide, are affected by many environmental factors such as temperature, room geometry and layout, and equipment loading and positioning. Injection rates and dwell times must also be calculated and validated for each unique chamber or room that you wish to decontaminate with agents of this type. Additionally, each piece of equipment added or removed or repositioned in these spaces requires new cycle development testing to be performed. On the other hand, for a true gas such as chlorine dioxide, cycle development consists of only a rough calculation of the chamber. The amount and positioning of equipment and items does not play a role in CD cycle development as gases will uniformly fill any space they are injected into regardless of environmental factors. This greatly simplifies validation efforts and easily ensures process efficacy and repeatability.

Factors Affecting Decontamination

Hard to Reach Areas

With chlorine dioxide gas, there are no issues with tight, hidden or difficult to reach areas, including microscopic cracks and crevices. Gasses by nature fill the space they are contained within evenly and completely. The chlorine dioxide molecule is 0.124 nm in size, far smaller than viruses, fungi, bacteria and their spores. This means that chlorine dioxide gas is able to contact organisms wherever they are in a space. Vapors are subject to hydrogen bonding, which clumps their molecules together and limits its movement in air.

Temperature

With chlorine dioxide gas, there are no issues with temperature or temperature gradients. As a gas, it does not condense out as VPHP does. With as little as one-degree temperature gradient, VPHP concentration can be affected. With VPHP, this small temperature difference can cause different concentrations throughout the chamber.

Cycle Development and Validation

There is no cycle development necessary for chlorine dioxide gas cycles as the process is forgiving enough to overcome the amount and position of equipment and materials within the space, and the temperature/humidity within the space With chlorine dioxide gas, easy validation of sterilization cycles is possible due to the accurate concentration monitoring capabilities of the gas.