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Laboratory & cleanroom3 min readLast updated September 2026

H₂O₂ fumigation: what a room must be capable of for decontamination to succeed

Room decontamination with gaseous hydrogen peroxide is regarded as residue-free and validatable. Whether it works reliably in operation, however, is decided not by the fumigation unit, but by the room envelope, ventilation and controls.

Key points

  • H<sub>2</sub>O<sub>2</sub> decomposes into water and oxygen – but its efficacy depends heavily on humidity, temperature and uniform distribution.
  • A leaky room loses active substance, endangers adjacent areas and cannot be validated reproducibly.
  • It is often not the contact time but aeration to below the occupational exposure limit that determines how long a room is out of service.
  • Airtightness, gas-tight shut-off dampers, penetrations, sensors and interlocks must be defined during planning, not at commissioning.

01Why hydrogen peroxide

In cleanrooms, animal facilities and isolation wards, entire rooms must be decontaminated at regular intervals or after an incident – including all surfaces that wipe disinfection cannot reach. Gaseous hydrogen peroxide (H2O2) has become established for this: it is strongly oxidising, with a suitable design it also covers spores, and at the end it decomposes into water and oxygen. The EU GMP Guide requires that the efficacy and distribution of such a fumigation process are understood and validated.

02The typical fallacy

Fumigation is often treated purely as an equipment question: you procure a fumigation unit, place it in the room and start the cycle. In practice, however, validation and operation fail elsewhere – because of leaky ceilings and penetrations, ventilation ducts that cannot be shut off gas-tight, materials that absorb H2O2 or are attacked by it, and aeration that releases the room only slowly.

03The principle: four phases, one measurement

A cycle runs in phases: the room is sealed off and brought to a defined humidity condition, then the concentration is built up, held for the validated contact time and finally reduced. Depending on the process, either the work is carried out below the dew point or a fine micro-condensation on the surfaces is deliberately sought – in both cases, humidity control is a key parameter. The room is only released once a measurement shows that the concentration is below Suva’s occupational exposure limit (MAK value).

Schematic curve of the H2O2 concentration over the phases preparation, conditioning, dwell and aeration until below the occupational exposure limitSCHEMATIC CYCLE OF A ROOM FUMIGATION WITH H2O2Preparationsealed, dryConditioningbuild-upDwellhold, validatedAerationdecay to limit value – often the longest phaseH2O2 in the room air (qualitative)TimeOccupational exposure limit (MAK)Release only after measurementSchematic, not to scale – curve and duration depend on process, room and ventilation
The cycle does not end with the contact time Schematic, not to scale

04Aeration determines downtime

The concentration during the contact phase is orders of magnitude above the occupational exposure limit. During aeration, it decreases approximately exponentially – the duration therefore depends on the ratio of the two concentrations and on the effective air change rate.

≈ 40 minFictitious calculation example with assumed values: reduction by a factor of 800 at ten air changes per hour, without catalyst – ln(800) / 10 h ≈ 0.67 h. Half the air change rate means twice the time.

A higher air change rate during aeration or catalytic decomposition directly shortens this phase. The ventilation system must be able to provide both.

05What this means for your project

  • Room envelope: closed, H2O2-resistant and non-absorbent surfaces, sealed connections up to the structural slab, sealed doors and penetrations, verified by an airtightness test.
  • Ventilation: gas-tight shut-off dampers, controlled pressure maintenance relative to adjacent rooms and a sufficiently high air change rate for aeration.
  • Penetrations: if a fumigation interface is located in a fire compartment wall, it must at the same time be gas-tight, closable and resolved in fire protection terms with proof of suitability for use.
  • Controls and sensors: operating modes with interlocking of doors and dampers, integration of the fire alarm system, H2O2 measurement in the room and in adjacent areas, release only on the basis of a measured value.
  • Material selection: check metals, seals and electronics for compatibility with oxidising agents.

Defining these points early in the room data sheets and the ventilation concept avoids expensive retrofitting – and creates the precondition for the process to be validated reproducibly later on.

Takeaway

A room can only be fumigated once it is airtight, can be aerated in a controlled way and its release is based on a measurement, not on the clock.

Standards and sources

  • EU GMP Guide, Annex 1 “Manufacture of Sterile Medicinal Products” (2022), section 4.34 et seq. – validation of disinfection and fumigation
  • SN EN 17272:2020 – Methods of airborne room disinfection by automated process
  • Suva, “Grenzwerte am Arbeitsplatz” (occupational exposure limits; current MAK values, www.suva.ch/grenzwerte)
  • Ordinance on Biocidal Products (OBP, SR 813.12)
  • VKF/AEAI fire protection regulations (fire protection standard and fire protection directives)

SEDC AG · Article from our internal training series “Technik Praxis”, abridged for clients and users.

Full version & expert discussion

More depth for your project.

The full version contains the conversion of concentration data, the derivation of the aeration time, the comparison of distribution variants with and without the ventilation system, and our checklist for room envelope, penetrations and controls. We are happy to go through it with you – applied to your installation.

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