Vaporized Hydrogen Peroxide Bio-Decontamination Q&A

Relative saturation and relative humidity graph
Piritta Maunu
Life Science Regulatory Compliance and Industry Expert​
Industrial Measurements
Life Science

Vaporized H2O2 bio-decontamination is a highly relevant topic especially within the life science industry but also other industries using the ecological H2O2 in bio-decontaminating equipment and facilities.

In our webinars "Room Bio-Decontamination with Vaporized Hydrogen Peroxide" and "Vaporized Hydrogen Peroxide Bio-Decontamination in Isolators and Transfer Hatches"  we have gone through several topics related to H2O2 bio-decontamination and we have received a lot of questions. The webinars are available on-demand via the above links, but let's go the questions and answers.

Please scroll down to see the Q&A section - the latest questions have been added on January 25th, 2018.

Could you describe once more what the difference is between RH% and RS%?

Relative humidity measures only vaporized water in the air. Relative saturation measures both vaporized water and vaporized H2O2 in the air.

Read a more detailed explanation in Vaisala PEROXCAP® Sensor for Measuring Vaporized Hydrogen Peroxide, Relative Saturation and Relative Humidity.

You are also welcome to listen to one of our on-demand webinars on the topic:

Room Bio-Decontamination with Vaporized Hydrogen Peroxide (webinar recording)

Vaporized H₂O₂ Bio-decontamination in Isolators and Transfer Hatches (webinar recording)

What do you mean by traceable H2O2 calibration?

a. Traceable measurement can be related to appropriate measurement standards, generally national or international, through an unbroken chain of comparisons

b. Vaisala’s HPP272 hydrogen peroxide measurement is traceable to the international system of units (SI) through national metrology institutes (NIST USA, MIKES Finland, or equivalent) or via ISO/IEC 17025 accredited calibration laboratories.

What is the difference between sterilization and bio-decontamination?

Definition for sterilization process is: Any chemical or physical process which destroys all life forms, with special regard to microorganisms (including bacteria and bacterial spores), and inactivates viruses. Therefore the terms "sterile" and "sterilization", describe the absence and the destruction of all viable microorganisms.

Bio-decontamination is defined as removal of microbiological contamination or its reduction to an acceptable level.

Main differences between sterilization and bio-decontamination are also explained on our related on-demand webinar called "Vaporized H2O2 Bio-Decontamination in Isolators and Transfer Hatches".

Why is a higher concentration of H2O2 used for food and beverage than for pharmaceuticals?

Typically in food and beverage industry you have continuous process where for example cups or bottles are bio-decontaminated prior to filling in. Typically very high concentration (e.g. 10000 ppm) for a short time (e.g. 8 seconds) is used to provide the required log reduction. The higher the ppm, the shorter can the bio-decontamination time be, in order to provide the required log reduction. Production turnaround time is the most important factor.

Can the probe be re-calibrated by the end user? If yes, please describe the method.

H2O2 is a very unstable gas and it is therefore difficult to make calibration in H2O2 environment. However, if you have, for example, a factory calibrated HPP272, and another HPP272 that you wish to calibrate, you can just compare the measurement results between these two. It is important that these two probes are installed close to each other to make sure they measure the same environment.

We are currently working on an onsite calibration capability for the HPP272 probe with Relative Humidity (RH). I.e. in the future you will be able to calibrate and adjust the HPP272 onsite using any humidity calibrator (for example Vaisala's HMK15) and Vaisala Insight software. With any humidity calibrator and the Insight software you are able to calibrate and adjust both H2O2 ppm and RH.


So in order to reach micro-condensation conditions you have to reach 100% RS?

Your sensor's Relative Saturation (RS) reading will show 100% when condensation starts. Here is a reference to an article that discusses the relationships between humidity, hydrogen peroxide concentration and micro-condensation:

"The Influence of Humidity, Hydrogen Peroxide Concentration, and Condensation on the Inactivation of Geobacillus stearothermophilus Spores with Hydrogen Peroxide Vapor"
Beatriz Unger-Bimczok, Volker Kottke, Christian Hertel, Johannes Rauschnabel
Journal of Pharmaceutical Innovation (2008) 3:123–133 DOI 10.1007/s12247-008-9027-1.

Published online: 8 May 2008 # International Society for Pharmaceutical Engineering 2008.


What is the tolerance for %RH & ppm?

HPP272 is designed for high humidities. It measures humidity from 0% to 100%. The ppm measurement range is up to 2000 ppm. HPP272 is not for safety level measurement. Our accuracy specifications starts from 10 ppm onwards.

Does H2O2 destroy DNA / RNA?

We know that in general RNA molecules are much more sensitive to degradation than DNA. It's also a well known fact that hydrogen peroxide ions cause oxidation of proteins, membrane lipids and DNA. [see Löffler G. and Petrides P. E.: Physiologische Chemie. 4 ed., p. 288, Springer, Berlin 1988, ISBN 3-540-18163-6 (in German)].

We haven't tested the effectivity of hydrogen peroxide against DNA. We would like to recommend to you that you search on the web if there are scientific studies made about H2O2 effectiveness against DNA/ RNA. Or you could make your own studies. Meanwhile, we would recommend other well known ways to destroy DNA and RNA to be sure about the effectivity. Such as UV-light alone or combined with higher temperature and specific chemical agents that are available commercially to destroy DNA and RNA residues. Such agents are typically used for example in PCR (polymerase chain reaction) applications.




Piritta Maunu

Life Science Regulatory Compliance and Industry Expert​

Piritta Maunu has 15 years of experience in biotechnology, having worked in several quality management positions. Maunu holds a degree of M.Sc. (Cell Biology) and is certified to teach with a specialty in General Biology, both degrees from the University of Jyväskylä, Finland. In her role at Vaisala, she supports the sales department, assists the quality department with audits, creates educational content for life science customers, and provides application support to R&D teams creating solutions for monitoring critical environments.



John Senger

Jul 25, 2018
Does this mean that all other HUMICAP/INTERCAP sensors are actually measuring RS in the presence of H2O2 vapor, when they are described as "Humidity Sensors" (e.g. HMD60Y, HMP110 sensors)?

Lars Stormbom

Jul 25, 2018
Thank you for your question. Yes, the indicated value of a normal HUMICAP sensor will be quite close to the saturation value.

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