FFP masks

The most promising processes for decontamination of FFP2 masks for reuse are:

• Steam sterilisation at 121˚C
• Sterilisation using hydrogen peroxide gas

The result of the treatment depends largely on the type/brand of FFP2 mask in combination with the process used. Results do not automatically extend to other types/brands of FFP2 masks or other processes. RIVM and Delft University of Technology (TU Delft) are testing several types of FFP masks reprocessed by different processes.
In addition to these reprocessing methods and for personal use only on a small scale, there is the possibility of reusing a disposable mouth-nose mask once after dry storage for at least 7 days.

Test results for sterilisation of FFP masks

In the most recent study, TU Delft carried out measurements on a series of sterilised respiratory protection FFP masks on behalf of RIVM. The effects of sterilisation for reuse (reprocessing) by means of steam sterilisation at 121°C for 15 minutes or hydrogen peroxide were examined. The table attached shows data on filtration effectiveness and fit value (indicating how well a mask fits the subject's face) for each combination of mask type, process type, and the number of reprocessing times. More information on the interpretation of the data, the study limitations and conditions for use of sterilized FFP masks can be found in the memorandum ‘Toelichting interpretatie meetgegevens FFP maskers’ (‘Notes to the interpretation of test data for FFP masks’, in Dutch).

Literature study on reuse of FFP masks

In the past 15 years, several studies have been conducted on methods for enabling reuse of single-use FFP masks. To gain insight into the available information on reprocessing and the methods used or researched in literature, RIVM conducted a literature study. The summary of the literature study lists decontamination methods that are largely suitable for small-scale use, and some methods suitable for larger-scale application (ethylene oxide and steam sterilisation at 121°C).