Cleaning Before VHP: Why Bio-Decontamination Does Not Replace It
VHP inactivates microorganisms on clean, exposed surfaces. It does not remove soil, residues or films — and some of them protect microorganisms or break the vapour down before it can act. This guide explains why cleaning comes first, what to remove, and how to fit cleaning and VHP into one contamination control routine.
- VHP is a surface bio-decontamination step, not a cleaning step: it removes nothing.
- Soil and films shield microorganisms; organic material can also decompose hydrogen peroxide before it acts.
- Biological indicators are clean carriers, so a validated cycle assumes clean surfaces — cleaning is part of the validated state.
- Remove liquids and dry surfaces: water films raise humidity and pull peroxide out of the vapour.
- Annex 1 expects cleaning to remove residues as part of the disinfection programme; VHP fits after cleaning, not instead of it.
What VHP does and does not do
Hydrogen peroxide vapour inactivates microorganisms it can reach on exposed surfaces. It does not lift dirt, dissolve residues or rinse anything away, and when the cycle ends whatever was on the surface is still there. A cycle is therefore only as good as the surfaces it is applied to.
This matters for validation as much as for practice. The biological indicators used to qualify a cycle carry spores on a clean carrier. A cycle shown to achieve a 6-log reduction on clean carriers has not been shown to do the same under a layer of dried product, protein or disinfectant residue. Cleaning is part of the validated state of the process.
How residues interfere
| Residue | Effect on VHP |
|---|---|
| Organic soil — product, protein, culture media, blood, dust | Shields microorganisms underneath it. Organic material, especially biological material containing the enzyme catalase, can also decompose hydrogen peroxide at the surface before it acts. |
| Disinfectant and detergent films | Build up with repeated use and form a layer over the surface. They can also make surfaces look clean while holding particles and microorganisms. |
| Powder residues (in isolators) | Shield the surface beneath; potent compound residues must be removed for operator safety in any case. |
| Water and liquids | Standing water and wet surfaces absorb peroxide, raise the humidity in the space and can cause local condensation. |
| Cellulose — paper, cardboard, wipes left behind | Absorbs vapour, lowers concentration nearby and lengthens aeration. See material compatibility. |
A practical sequence
- Remove. Take out waste, packaging, paper, liquids and anything that does not need to be treated.
- Deal with spills first. Biological spills are treated with a liquid disinfectant according to the spill procedure before general cleaning.
- Clean. Remove visible soil with a suitable detergent, from clean to dirty areas and from top to bottom.
- Remove residues. Wipe with water for injection or purified water, or a residue-removal step defined in the cleaning procedure, so detergent and disinfectant films do not build up.
- Dry. Let surfaces dry; remove standing water from floors, sinks and equipment.
- Prepare for VHP. Open cabinets and equipment, arrange the load, seal the room — see preparing a room for VHP.
- Run the validated cycle and release the space after aeration.
In isolators
Inside an isolator the same logic applies at a smaller scale. Between campaigns or products, the chamber is cleaned to remove product and powder residues, wiped to remove cleaning agent residues and allowed to dry before the VHP cycle. Components that will be in the chamber during the cycle should be clean and dry, and the load configuration should match the one used in qualification. For potent compounds, cleaning is also what protects the next operator who opens the chamber, and its effectiveness is verified separately.
Where VHP sits in the disinfection programme
EU GMP Annex 1 (2022) expects a disinfection programme that includes cleaning to remove residues, the use of more than one type of disinfectant, and a sporicidal agent. VHP is one way of applying a sporicidal step reproducibly — it reaches surfaces that manual wiping misses, and its parameters are recorded. It complements routine manual cleaning and disinfection; it does not replace them.
A common pattern in cleanrooms is routine manual cleaning and disinfection, with VHP after shutdowns, construction, contamination events and at a defined periodic frequency. In isolators, VHP is usually the decontamination step before every campaign, after cleaning.
References
EU GMP Annex 1 (2022), Manufacture of Sterile Medicinal Products
USP <1072> Disinfectants and Antiseptics
PDA Technical Report No. 70, Fundamentals of Cleaning and Disinfection Programs for Aseptic Manufacturing Facilities
PDA Technical Report No. 51, Biological Indicators for Gas and Vapor-Phase Decontamination Processes
Fenggu equipment for this
Mobile VHP room sterilizer
Wheeled unit for spaces up to 300 m³, with scheduled and remote start.
View specifications →FG-VHP-C1000 / C2000HVAC-integrated VHP system
Distributes vapour through the existing AHU to treat a whole suite. Standard capacities 1,000 and 2,000 m³.
View specifications →FG-ISO-AFAseptic filling isolator
Integrated VHP bio-decontaminates exposed interior surfaces before every campaign.
View specifications →Related application guides: Cleanroom and room decontamination · Isolator and RABS decontamination
Common questions
Do I need to clean before VHP decontamination?
Yes. VHP inactivates microorganisms on exposed surfaces but removes nothing. Soil and residues shield microorganisms and organic material can break down hydrogen peroxide, so surfaces should be cleaned and dried first.
Can VHP replace manual cleaning and disinfection in a cleanroom?
No. It complements them. EU GMP Annex 1 expects cleaning to remove residues and a disinfection programme that includes a sporicidal agent; VHP is a reproducible way to apply the sporicidal step.
Why must surfaces be dry before VHP?
Standing water and wet surfaces absorb hydrogen peroxide, raise the humidity in the space and can cause local condensation, all of which make the cycle less effective and less reproducible.
Does organic soil affect hydrogen peroxide?
Yes. Organic material shields microorganisms, and biological material containing catalase can decompose hydrogen peroxide at the surface before it acts.
How do biological indicators relate to cleaning?
Biological indicators carry spores on clean carriers. A cycle qualified with them assumes clean surfaces, so cleaning is part of keeping the process in its validated state.
Have a specific space or load in mind?
Send the volume, the materials and what you need to prove. An engineer replies with a recommended setup and what validation will involve.