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From: Food Quality & Safety magazine, February/March 2011

Elevating Room Sanitation Quality

Hydrogen peroxide vapor has broad-spectrum efficacy, excellent material compatibility

by Martin Orlowski

To deliver hydrogen peroxide vapor, a generator is typically placed inside the target area and fully controlled from a remote location.
To deliver hydrogen peroxide vapor, a generator is typically placed inside the target area and fully controlled from a remote location.

In recent years, the focus on the environmental quality of the food production landscape has increased. Although far from being a new problem, high-profile cases resulting in sickness and death traced back to the manufacturing process have caused the industry to reassess contamination control strategies, an issue currently under discussion in the Senate and inherently linked to food safety.

Some level of contamination control naturally already exists and, given the diversity in environmental production types, varies appropriately. But due to the frequency and severity of contamination occurrences—and the associated regulatory intervention—the procedures often used fall short of reasonable expectations. This article aims to highlight some of the issues and challenges involved with current techniques while considering the use of hydrogen peroxide vapor (HPV), a well documented and Food and Drug Administration (FDA) approved technology, as a means of elevating the cleaning and sanitizing processes in both wet and dry environments.

The challenge of room and space contamination control is not new. Many other industries outside of food production have realized the benefits of improving environmental quality with a view to minimizing contamination risk. Among others, these include pharmaceutical production, research laboratories, and health care. Although each application comes with a unique set of challenges and expectations specific to the sector, various terminologies are casually used to describe the contamination control process. The most basic of these is “to clean,” but others include words and phrases such as sanitize, decontaminate, remove airborne pathogens, deep clean, and sterilize. All of these ultimately share a common end goal: to offer a high level of bioburden reduction in a safe, consistent, and operationally effective manner.

Traditional approaches to cleaning concentrate efforts on equipment pieces and food contact surfaces; the general environment is somewhat of an afterthought. These efforts often adopt a “manual” or “spray and pray” type of approach that allows for a confirmation of success (or failure) at a point location using visual verification or swab testing when the process is complete. Even if you overlook the issue of using the human eye to confirm the removal of unwanted microorganisms, this approach is limited because, outside the tested area, you will find no indication of achievement; this represents the minimal accountability level. Take, for example, a targeted alcohol sprayer. The motivation of the individual operating the system is crucial for ensuring efficacy through suitable distribution and sufficient contact time. Under ideal circumstances, such technologies work, but ideal circumstances do not represent everyday challenges.

Tryptone soy broth growth media is used to determine bacterial growth and the success or failure of decontamination.
Tryptone soy broth growth media is used to determine bacterial growth and the success or failure of decontamination.

Fully Automated Execution

Some will argue that well-written protocols like hazard analysis and critical control points address many concerns, including issues of repetition—a key flaw in manually controlled processes. Even with well-written sanitation standard operating procedures, however, two individuals will execute a task with different performance standards. Consequently, removing the human element from a process and its subsequent automation is attractive, and efforts have been made within the food production environment to achieve this goal. Chlorine dioxide liquid “foggers” have been widely used. Unfortunately, in addition to the long-term material compatibility associated with all chlorine-based agents and the relatively inconsistent levels of bioburden reduction (due in part to the line-of-sight limitation), the process is messy. Before operations can be resumed, every surface must be wiped down, a step that allows for potential recontamination. Such issues do not exist with the HPV decontamination process, which allows for a fully automated execution. A generator, which may be pumped in from an external location if desired, is typically placed inside the target area and fully controlled from a control panel at a remote location. The process is applied daily in areas ranging from small single rooms to entire buildings of around 3,500,000 cubic feet, large enough to accommodate most production facilities. Most importantly, however, the process can be fully validated and demonstrates repeatability in accordance with FDA regulations.

The HPV process can only be applied in vacant areas and works by distributing the vapor. The vapor results from the controlled flash evaporation of a liquid hydrogen peroxide solution. It takes about two hours to achieve the right conditions; this state is then maintained for approximately 10 minutes. The final phase catalyzes the agent into harmless byproducts, water vapor and oxygen, returning the environment to its original, but now sterile, condition. This residue-free characteristic aided the initial success of the technology, along with the added benefits of ease of verification and material compatibility over both the long and short terms. The breakdown element of water vapor is registered as just a slight, temporary elevation of humidity conditions. The process can be conducted within a range of 10% to 90% relative humidity and a wide temperature range—nothing beyond the typical ambient variation experienced naturally throughout the year. It does not leave behind puddles of water that may require removal, which is significant to plants with dry operations.

Well Established in Other Industries

Hydrogen peroxide vapor use is well established in other industries, many of which made similar transitions from primitive cleaning techniques. Around 95% of the world’s pharmaceutical production companies, likely one of the most scrutinized industries in existence, use HPV for sterilization. The FDA has accepted the technology, which has been scrutinized to a degree far beyond anything required in other industries. For nearly 20 years, the technology has been used with no suitable alternative available. From its conception, HPV has evolved from a focus on small, contained systems and chambers to larger volumes, such as rooms and buildings.

After passing the rigorous demands of the pharmaceutical industry, the technology received a lot of attention from the health care market, where the process is widely used in patient rooms and surgical suites with a view to reducing transmission rates of hospital-acquired infections such as methicillin-resistant Staphylococcus aureus and Clostridium difficile. Manian and colleagues showed that, compared to a single HPV cycle run in a patient room, four manual bleach wipe downs were needed to achieve an equivalent result.

While the target organisms in food production plants are often different from those found in hospitals, obvious parallels can be drawn from the Manian findings. Any similar study in food production environments would likely find even more extreme results, because the latter are often factors of hundreds of times larger in size and complexity than a typical hospital room. Within a hospital room, one can reasonably expect to apply cleaning agents to most surfaces, but can the same be said of areas with 100-foot ceilings and complex production equipment lines? As a result, manufacturers must consider both the distribution and the efficacy of the HPV process.

Within the target environment, every single nook and cranny and piece of equipment will be exposed to HPV, ensuring a high level of biological reduction.

Not a Line-of-Sight System

HPV technology is not a line-of-sight system. Hydrogen bonding characteristics mean the technology is poor at passive diffusion; however, this limitation is overcome by using high-kinetic energy injection nozzles to ensure thorough distribution. This trait contributes significantly to safety, an aspect discussed further below, because any leak tends to remain resident in its locality.

Within the target environment, every single nook and cranny and piece of equipment will be exposed to HPV, ensuring a high level of biological reduction. This reduction can be demonstrated numerically to show a minimum of a six-log reduction of a Geobacillus stearothermophilus bacterial spore challenge. To perform this test, commercially available stainless steel coupons inoculated with the bacterial spores are placed at predetermined locations. The coupons come prepackaged in small Tyvek pouches that allow the vapor to penetrate accordingly. On completion of the decontamination cycle, the pouches are removed and the coupons incubated in tryptone soy broth growth media. The analysis that follows is a simple pass-fail test: A turbid growth media tube indicates bacterial growth and process failure; conversely, a clear solution indicates the successful deactivation of all the bacterial spores. In the event of a failure, an analysis may be conducted to determine severity.

The number of indicators required depends on the size, layout, and severity of circumstance. Demonstrating thorough distribution of the decontamination agent is of utmost importance, so extreme locations like the corners of rooms and regular intervals in between and around equipment are logical starting points. Following a serious contamination, the use of more indicators adds credibility and support to regulatory scrutiny.

G. stearothermophilus is used as a challenge organism for several reasons. Besides being easy to handle, obtain, and analyze, it is one of the microorganisms that is most resistant to HPV. It is the same challenge organism used in steam sterilization. Over the years, a number of correlative studies have been performed to demonstrate the parallels between the deactivation of G. stearothermophilus spores and other microorganisms. Not surprisingly, such tests have shown that all other bacteria, viruses, fungi, and such are deactivated much sooner than the G. stearothermophilus challenge organism. Once G. stearothermophilus spore strips have been successfully deactivated in an environment, it can safely be assumed that Salmonella has been removed as well.

The issue of safety is an interesting topic with regard to HPV application. HPV exposure at certain concentration levels is toxic to humans, which is not surprising considering that the technology exists to kill microorganisms (the Occupational Safety and Health Administration permissible exposure limit—the level at which an area is deemed safe for re-entry—sits at 1 part per million, and the immediately dangerous to life and health level is fixed at 75 parts per million).

It stands to reason that a target area must be both vacant and sealed for an intended application. Consideration must be given to the manageability of the agent, which is a simple matter in the case of HPV. Containing HPV and maintaining safe conditions in the event of a possible leak become crucial during detection, which is conducted using handheld sensors. In the exceptional event of a leak (the process can be run under a negative pressure), the operator has substantial time to react and address a failed seal.

The example of health care is one of the most useful because, just as with many food production environments, the infrastructure of most hospitals was not designed with HPV containment in mind, yet rooms are treated on a daily basis with patients in adjacent rooms and hospital traffic in hallways immediately outside. With the number of applications in the hundreds of thousands globally, there is no record of any incident of concern.

Benefits Outweigh Implementation Costs

Although the initial implementation of such a technology comes at a slight premium, the benefits realized from regulatory, safety, and operational standpoints far outweigh the costs. Traditionally, the use of HPV technology required companies to consider factors specific to the environment such as size, construction, and environmental conditions. These elements, combined, helped to determine the parameters used to describe a successful cycle and its influence on overall performance. Today, many systems have integrated parametric control algorithms that limit the operator input to the dimensions of the system being decontaminated.

With changes relating to improving food safety imminent, this technology should be considered during the preliminary phases of construction projects and expansions. With forward thinking and planning, the level of integration can be elevated while downtime and operational impact within a plant are minimized. It is likely that, with regulatory influence, the future of the food production environment will draw an ever-increasing number of parallels with other industry types, such as aseptic processing and containment.

With its broad spectrum efficacy, excellent material compatibility, fully manageable safety, and excellent process control supported by robust validation, HPV technology is easily accessible for a variety of existing large-scale facilities to destroy microorganisms in an area following a contamination—or as a preventative means. It also offers an opportunity to elevate the standard to which food production environments are cleaned on a routine basis.

Orlowski is the head of sales, life sciences, at Bioquell Inc. Reach him at or (215) 682-0225.


  1. Centers for Disease Control and Prevention (CDC). NIOSH pocket guide to chemical hazards: hydrogen peroxide. Available at: Accessed January 23, 2011.
  2. Manian FA, Griesenauer S, Senkel D. Impact of an intensive terminal cleaning and disinfection (C/D) program involving selected hospital rooms on endemic nosocomial infection (NI) rates of common pathogens at a tertiary care medical center. Paper presented at: Fifth Decennial International Conference on Healthcare-Associated Infections; March 18-21, 2010; Atlanta.



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