Opinion: Airtightness for Decontamination by Fumigation of High-Containment Laboratories.

Introduction: While the European legislation states that laboratories of high-containment must be sealable for fumigation, they do not prescribe a minimal value for airtightness. Starting from a previous study in which we measured the airtightness in 4 BSL-3 laboratories with blower-door tests, we discuss the connection between airtightness and a successful decontamination by fumigation.

Methods: Biological indicators (BIs) consisting of spores of on metal disks were laid out in laboratories of different levels of airtightness before performing a fumigation with aerosolized hydrogen peroxide using an automated device, according to the manufacturer's instructions.

Results: Incubation of all BI disks placed in the facility with the highest level of airtightness showed complete inactivation of spores. However, in the facility with a lower level of airtightness, not all spores were inactivated.

Discussion: Air leaks might be a factor in the outcome of the decontamination of a room by fumigation, as seen in the laboratory with a lower level of airtightness, but other factors associated with the fumigation process might also be critical for a successful decontamination.

Conclusion: We argue that a validation of the decontamination procedure, before first use or after important renovations of a laboratory of high-containment, is a more effective endpoint than reaching a predefined level of airtightness.