The vaporized hydrogen peroxide (VHP) apparatus applies a highly corrosive and concentrated 35% hydrogen peroxide (H2O2) “film” to surfaces. (1)
This is needed to achieve the EPA mandated 6-log reduction performance standard for disinfection claims.
The VHP process poses various problems.
Introduction & Summary
Extremely high percentage of hydrogen peroxide liquid is turned into a vapor by using a hot vaporization surface to flash the hydrogen peroxide solution from a liquid into a gas. The resultant gas that is formed, is then flowed into the targeted room. A high concentration of the 35% hydrogen peroxide gas must first accumulate in the room and then dwell for a specific amount of time, forming a “film” of the 35% hydrogen peroxide on surfaces within the room, before the process is complete and the room air can start to be filtered to remove the concentrated gas.
Disadvantages of vaporized hydrogen peroxide (VHP):
- Corrosive (uses at least 30-35% hydrogen peroxide).
- Can be deactivated by the enzymes catalase and peroxidase. (98)
- Long time to achieve efficacy (2.5-2.9) hours - minimum
- Entire process can take up to (8 hours) start to finish. (99)
- Long time to achieve efficacy (2.5-2.9) hours start to finish.
- Dangerous vapor - accidental exposure to vapor can cause worker injury.
- Fire hazard - all cellulose materials must be removed from room.
- Room must be well sealed due to dangerous vapor.
- Catalytic converter failure would deny quick room access.
- Room materials can be further jeopardized if the catalytic converter failed.
- Incompatible with certain materials such as nylon, neoprene, certain anodized aluminum, and some epoxides, as well as equipment containing extensive color-coded wire insulation. (100)(101)(102)
- Can damage electronic equipment. (102)
The problems with vaporized hydrogen peroxide (VHP) technology:
1) FIRE HAZARD - Cellulose material in the room must be removed because the 35% hydrogen peroxide gas and the resulting moist film that coats everything in the room, is a very strong oxidizer and cellulose material (ie: paper in any form) can ignite presenting a fire hazard.
2) LONG TREATMENT TIME - The treatment process is extremely long. In the research paper by Dr. Boyce et al., titled "Comparison Of The Microbiological Efficacy Of Hydrogen Peroxide Vapor and Ultraviolet Light Process For Room Disinfection", [Infection Control And Hospital Epidemiology, May 2002, Vol 33, No. 5] the following treatment times were found for Bioquell's patient room disinfection process (entry to exit) for hospital patient rooms:
Mean time = 153 minutes / 2.5 hours
Minimum time = 140 minutes / 2.3 hours
Maximum time = 177 minutes / 2.9 hours
The reason for this extremely long process time is that their process depends on the amount of disinfection agent that interfaces with the targeted surfaces. Gasses by definition have significantly less mass or substance per cubic centimeter of area than say an aerosol existing in that same volume of space. Therefore, it takes longer to fill the room with enough disinfecting agent to be efficacious.
The total treatment time is also impacted by the properties of the chemical used for disinfection and the contact time that is needed between the applied chemical and the targeted microorganism(s) in order to achieve the desired Log Reduction or kill. Finally, the treatment time is also impacted by the long time that is needed to reduce the 35% hydrogen peroxide vapor to safe levels within the room.
3) HUMIDITY & TEMPERATURE EFFECTS - Vaporized hydrogen peroxide (VHP) technology can be impacted by temperature and humidity fluctuations and therefore dew point. If the conditions and treatment process are not kept just right during the treatment process, the outcome can be impacted and pooling of the 35% hydrogen peroxide liquid can occur.
4) DANGEROUS TO EMPLOYEES - The Bioquell vaporized hydrogen peroxide system emits a 35% hydrogen peroxide gas into the treated room. The room must be be fully dry and clear of any vapor after treatment because 35% hydrogen peroxide will substantially burn human skin when in liquid form (if the hydrogen peroxide has pooled), and/or burn lung tissue if the vapor is inhaled.
The room door(s) must be closed and sealed airtight, and cannot be accidentally opened for any reason, posing a serious health threat to those who open the door(s). Leaking 35% H2O2 gas is also an obvious health concern if the door(s) and exit vent(s) is not taped correctly.
If room entry is necessary during the Bioquell process for any reason (ie: the vapor removal system fails), the Bioquell MSDS sheet specifically states that activated charcoal respirator filters cannot be used (oxidizable sorbants), and only self contained breathing apparatus (SCBA) or approved air supply line systems (ALR), should be used with the recommended protective clothing and shoes.
The Bioquell system deposits a chemical percentage liquid film onto room surfaces consisting of 35% hydrogen peroxide. In addition to being a fire hazard to cellulose materials, the 35% hydrogen peroxide is also corrosive.
Basic Comparison Between Altapure and Vaporized Hydrogen Peroxide (VHP):
|Paper Fire Hazard||No||Yes|
|Treatment Time||< 50 Minutes||2.3+ Hours|
|Hydrogen Peroxide Amt.||0.88%||35%|
|6+ Log Reduction – Spores||Yes||Yes|
|Temp. & Humidity Sensitivity||No||Yes|
(1) Bioquell Website, 07/24/18: https://www.bioquell.com/life-sciences/our-technology-for-life-sciences/why-bioquell-technology/
(102) EPA/DHS Report - "Compatibility of Material and Electronic Equipment With Hydrogen Peroxide and Chlorine Dioxide Fumigation Assessment And Evaluation Report, Document: EPA/600/R-10/169.