Vaporized hydrogen peroxide (trademarked VHP, Retrieved February 2016. also known as hydrogen peroxide vapor, HPV) is a

vapor In physics, a vapor (American English) or vapour (Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is a substance in the gas phase at a temperature lower than its critical temperature,R ...

form of

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscosity, viscous than Properties of water, water. It is used as an oxidizer, bleaching agent, and antiseptic, usua ...

(H₂O₂) with applications as a low-temperature

antimicrobial An antimicrobial is an agent that kills microorganisms (microbicide) or stops their growth (bacteriostatic agent). Antimicrobial medicines can be grouped according to the microorganisms they are used to treat. For example, antibiotics are used aga ...

vapor used to decontaminate enclosed and sealed areas such as laboratory workstations, isolation and pass-through rooms, and even aircraft interiors. Retrieved September 2008.

Use as sterilant

Regulatory status

VHP is registered by the U.S.

Environmental Protection Agency Environmental Protection Agency may refer to the following government organizations: * Environmental Protection Agency (Queensland), Australia * Environmental Protection Agency (Ghana) * Environmental Protection Agency (Ireland) * Environmenta ...

as a ''sterilant'', which the EPA defines as "a substance that destroys or eliminates all forms of microbial life in the inanimate environment, including all forms of vegetative bacteria, bacterial spores, fungi, fungal spores, and viruses". As a sterilant, VHP is one of the chemicals approved for decontamination of

anthrax Anthrax is an infection caused by the bacterium '' Bacillus anthracis'' or ''Bacillus cereus'' biovar ''anthracis''. Infection typically occurs by contact with the skin, inhalation, or intestinal absorption. Symptom onset occurs between one ...

spores from contaminated buildings, such as occurred during the

2001 anthrax attacks The 2001 anthrax attacks, also known as Amerithrax (a portmanteau of "United States, America" and "anthrax", from its FBI case name), occurred in the United States over the course of several weeks beginning on September 18, 2001, one week after th ...

in the U.S. Retrieved September 2008. It has also been shown to be effective in removing exotic animal viruses, such as

avian influenza Avian influenza, also known as avian flu or bird flu, is a disease caused by the influenza A virus, which primarily affects birds but can sometimes affect mammals including humans. Wild aquatic birds are the primary host of the influenza A viru ...

and

Newcastle disease Virulent Newcastle disease (VND), formerly exotic Newcastle disease, is a contagious viral avian disease affecting many domestic and wild bird species; it is transmissible to humans. Though it can infect humans, most cases are non-symptomati ...

from equipment and surfaces.

Application

VHP is produced from a solution of liquid H₂O₂ and water, by generators specifically designed for the purpose. These generators initially dehumidify the ambient air, then produce VHP by passing aqueous hydrogen peroxide over a vaporizer, and circulate the vapor at a programmed concentration in the air, typically from 140 ppm to 1400 ppm, depending on the infectious agent to be cleared. Retrieved September 2008. By comparison, a concentration of 75 ppm is considered to be "Immediately Dangerous to Life or Health" in humans. After the VHP has circulated in the enclosed space for a pre-defined period, it is circulated back through the generator, where it is broken down into water and oxygen by a catalytic converter until concentrations of VHP fall to safe levels (typically <1 ppm). Alternatively, the VHP is vented to the outside air, in cases where recapturing of the VHP is not needed.

Use in hospitals

Vaporized hydrogen peroxide has been investigated as an airborne disinfectant and infection control measure for hospitals and has been shown to reduce incidence of

nosocomial A hospital-acquired infection, also known as a nosocomial infection (from the Greek , meaning "hospital"), is an infection that is acquired in a hospital or other healthcare facility. To emphasize both hospital and nonhospital settings, it is s ...

infections from several pathogens. ''

Clostridioides difficile ''Clostridioides difficile'' ( syn. ''Clostridium difficile'') is a bacterium known for causing serious diarrheal infections, and may also cause colon cancer. It is known also as ''C. difficile'', or ''C. diff'' (), and is a Gram-positive spec ...

'' associated disease, VRE and

MRSA Methicillin-resistant ''Staphylococcus aureus'' (MRSA) is a group of gram-positive bacteria that are genetically distinct from other strains of ''Staphylococcus aureus''. MRSA is responsible for several difficult-to-treat infections in humans. ...

are all associated with environmental contamination. H₂O₂ vapor has been used in hospitals to eradicate causal agents, ''e.g.'', antibiotic-resistant ''

Klebsiella pneumoniae ''Klebsiella pneumoniae'' is a Gram-negative, non-motile, encapsulated, lactose- fermenting, facultative anaerobic, rod-shaped bacterium. It appears as a mucoid lactose fermenter on MacConkey agar. Although found in the normal flora of the mo ...

'', from the environment and prevent infection of subsequent patients.

Monitoring technologies

OSHA The Occupational Safety and Health Administration (OSHA; ) is a regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. The United States Congress established ...

mandates a PEL of 1.0 ppm (1.4 mg/m ) for HPV. Typically, safe working environments around sterilization equipment is achieved with electrochemical

sensor A sensor is often defined as a device that receives and responds to a signal or stimulus. The stimulus is the quantity, property, or condition that is sensed and converted into electrical signal. In the broadest definition, a sensor is a devi ...

s capable of measuring in the parts per billion and low parts per million levels. These sensors are typically inexpensive and limited to ambient conditions. Moreover, HPV electrochemical sensors are often located near the sterilization equipment to detect possible leaks during the sterilization cycle. In 2014, Advanced Sterilization Products (ASP), sovaldi the manufacturer of the Sterrad hydrogen peroxide gas plasma sterilizer, issued a letter to hospital risk managers warning them that hydrogen peroxide residues may be found in the sterilization load. HPV being present in the sterilization load, could lead the accidental exposure of hospital staff. Monitoring hydrogen peroxide levels inside the sterilization chamber during the sterilization cycle can be challenging. Technical issues such as condensation, vacuum, and high concentration have prevented many sensing technologies such as electrochemical sensors from providing real-time monitoring of H₂O₂ concentration. Under these conditions, optical methods such as spectroscopy can be used to ensure that lethal concentrations of H₂O₂ are achieved in the sterilization chamber.

Dangers of manipulation

Hydrogen peroxide vapors and fumes can irritate and damage the skin, the respiratory tract, and the eyes. Extreme precautions must be taken when manipulating hydrogen peroxide, and it must not be considered harmless.

References

{{Reflist Hydrogen peroxide Antiseptics Disinfectants Sterilization (microbiology)