**2. Hybrid hydrogen peroxide via pulse technology**

One of the biggest challenges to any disinfectant application is ensuring a thorough and consistent disinfectant exposure to contaminated surfaces for an effective contact time. To achieve success, fogging technologies must perform a complicated dance between the amount of chemical injected, temperature, humidity, dew point, and method, all of which can affect efficacy from one application to the next. To answer this need, CURIS System designed and patented the concept of replenishing any naturally decomposing solution and called it Pulse technology, simplifying the complicated balance of a successful disinfection. Combining a 7% hydrogen peroxide solution with a calibrated fogging device, this HHP system delivers hybrid

### *Hybrid Hydrogen Peroxide for Viral Disinfection DOI: http://dx.doi.org/10.5772/intechopen.100237*

hydrogen peroxide, a mixture of gaseous and micro aerosol particles. While effective in a liquid solution, fogging with hydrogen peroxide in this hybrid form increases the availability of each H2O2 molecule, maximizing oxidation opportunities and leading to the destruction of pathogens on surfaces. Beyond just inactivating pathogens, this oxidation causes a physical destructive action of pathogen components, which further delineates this substance as a decontaminant as defined by the BMBL.

A fundamental distinction of this system is its ability to disperse a lower concentration of 7% hydrogen peroxide at calibrated intervals, maximizing contact time while using less H2O2 to achieve microbicidal efficacy. The HHP device operates by delivering the HHP mixture in a two-part process. First, it fills an enclosure with disinfecting fog to an optimal level for killing pathogens. Second, it maintains the fog at the optimal level without oversaturation by periodically injecting more solution into the space being treated, and thereby prolonging the active contact time of the H2O2 (**Figure 1**). This not only helps to keep surfaces dry, it also reduces sensitivity to variations in temperature and other factors. One might consider this similar to cruise control in a vehicle—the initial phase continuously revs the engine to get the vehicle up to speed, while the second phase uses the engine just enough to keep it at the cruising speed without exceeding the limit. In the case of disinfection, it means keeping the fog concentration at the optimum "kill" level to achieve efficacy in a relatively short time, yet without exceeding this optimum level to the point where the fog condenses on surfaces in the treatment area.

### **2.1 Chemical concentrations and safety implications**

With a concentration of 7% H2O2, the solution, known as CURoxide™, is below the 8% hazard threshold [27, 28]. Being below the threshold means special shipping considerations are not required. Moreover, this enables safer handling for personnel than the 35–59% H2O2 solutions traditionally employed for fogging applications [18, 29–31]. Likewise, the 7% solution is safer for laboratory materials than the 28.1–52% concentration of corrosive industrial strength grade hydrogen peroxide [27, 32]. This material safety (compatibility) is perhaps most evident when

#### **Figure 1.**

*Pulse HHP Cycle. Hydrogen peroxide released as a vapor or aerosol begins a natural decomposition into water and oxygen within 10 minutes. Most fogging delivery methods require longer contact time. Pulse technology periodically replenishes active hydrogen peroxide during the decontamination cycle, prolonging the effective contact time, and promoting an optimal pathogen kill zone.*

considering how the hydrogen peroxide concentration of a solution will evolve when the solution transitions through states of matter. Hydrogen peroxide is more resistant to leaving the liquid state and more likely to return to it than the water in the solution. When transitioning from vapor back into liquid, this can result in surface condensation at more than double the initial liquid concentration (**Figure 2**). At 7% H2O2, the HHP solution remains below the 45% known level of material incompatibility [33].

The levels of particle concentration used in typical high-level disinfection are of particular concern to facility managers. These concerns may be lessened by employing lower particle-producing products. Technologies utilizing formaldehyde, chlorine dioxide, and high concentration H2O2 operate at concentrations as high as 1,400 parts per million (ppm) [34–36]. By contrast, the HHP 7% solution has a lower operating concentration of approximately 138 ppm [37]. Traditional vaporized approaches require a concentration that is up to 10 higher than the lower 7% H2O2 concentration enables, which accordingly may result in a greater risk to personnel from leakage with typical high concentration systems [38]. This is particularly important because, according to the National Library of Medicine, "Inhalation of vapors from concentrated (greater than 10%) solutions may result in severe pulmonary irritation" [39]. This may be why there is a substantial safety concern among facility managers when it comes to typical fogging approaches, as these approaches utilize caustic chemicals at very high concentrations which are known to penetrate through gaps as small as a keyhole [38, 40].
