The benefits of using dry vapour (VHP)

Choosing the right method of decontamination for your cleanroom, laboratory, veterinary practice or hospital can be a difficult process. Mike Aitchison, Managing Director @ BDL explains the benefits of using vapourised hydrogen peroxide (VHP), over the traditional chlorine dioxide and formaldehyde treatments in the fumigation of equipment and facilities.

“The first benefit of using VHP arises from a health and safety standpoint. Both chlorine dioxide and formaldehyde pose some serious safety concerns, and pose a risk for occupants of buildings, as well as decontamination operatives.

In its normal state, chlorine dioxide is carcinogenic, and when exposed to water and light, forms a combination of chlorine gas and hydrochloric acid. Even at very small levels, the inhalation of chlorine gas is fatal, so operatives need to be extremely careful to avoid leaks, and surrounding rooms need to be evacuated before chlorine based decontamination can commence.

Formaldehyde is carcinogenic, and can react strongly with other cleaning agents like hydrochloric acid to create other carcinogenic by-products. Since fumigation with formaldehyde often occurs following disinfection, the subsequent formation of carcinogenic by-products and residues can be a real danger. Another issue regarding formaldehyde’s safety comes from its flammability. It mixes with air to create a potentially explosive combination and, in extreme cases, fires have been known to break out during the course of formaldehyde fumigation.

VHP has the benefit of being non carcinogenic, and non diffusive, turning to oxygen and water vapour after use, whilst leaving no residues. Its safety means that it can be used to decontaminate rooms adjacent to those being used, without exposing the occupants to any health risks.

VHP is also more flexible than the more traditional alternatives. The decontamination effectiveness of both chlorine dioxide and formaldehyde are heavily dependent on the temperature and humidity of the target area, and require strict levels to work correctly. VHP, on the other hand, can be used at a range of room temperatures and humidity levels, without its efficiency being affected. This is especially useful when working in large spaces where environmental factors such as temperature are difficult to control and maintain.

Another issue arising from the use of formaldehyde and chlorine dioxide comes from the time it takes to complete these processes. Initial fumigation with formaldehyde takes at least 12 hours to work properly. After this process, it usually takes another 24 hours to vent the toxic vapour, and more time still to clean off the residues before the room or building is safe to use again.

Whilst the fumigation process is faster with chlorine dioxide, the time it takes to prepare the room or building makes it a lengthy process. Before fumigation can begin, room temperatures and humidities must be raised to 21C and 70% respectively. Due to its temperamental nature, if these conditions cannot be achieved or maintained during fumigation, the process may have to be stopped and restarted. With chlorine dioxide, it is also essential that adjacent rooms are evacuated before the process begins.

VHP has none of these problems. Typically, rooms can be completely decontaminated in less than 90 minutes, and whole buildings can be fumigated within a day. After completion, it is typically only 2 hours before the rooms are clean, safe and ready to use again.
Overall, the benefits of hydrogen peroxide vapour in decontamination makes it the best choice for almost all applications, from small medical or laboratory equipment, to cleanrooms, wards, laboratories and buildings.  It outperforms both chlorine dioxide and formaldehyde on almost every level, from the speed of application, to health and safety. At BDL, we use VHP in all our decontamination services.”