Laboratory to carry out complex safety tests on the masks, checking the filtering power and microbiological purity of surgical masks

Paola Motetti
University of Bologna


 
Francesco Saverio Violante
University of Bologna

Abstract
During the recent period of coronavirus emergency, Italy has faced with a dramatic shortage of surgical masks to protect first health personnel and foremost common population.
In order to respond to the needs of the community, to speed up, promote and improve the spread of protective devices, many companies in the region have offered to produce masks and other medical devices, also urged by a ministerial decree which provided incentive measures in this direction.
Therefore, the validation of medical devices according to the standards has become an urgency together the production of them.

To make this procedure more accessible, the Bologna University has activated an interdisciplinary working group that has created a laboratory capable of evaluating, testing and declare the compliance of surgical masks with the EN 14683 standard (Type I or II or IIR) and with the ISO 10993 standard.

It is the first laboratory in Italy that tests protections for medical use according to EU standards, testing 10 50 different types of surgical masks every day. Orders arrive from all over Italy but also from abroad.

The test lines were built using tools and materials present in different laboratories of the University, together with others supplied on loan from the University of Venice and in pieces built ad hoc with a 3D printer at the DIN internal laboratory of the Bologna University. In particular, chemical engineering, occupational medicine and microbiology experts from the University of Bologna have created four systems dedicated to checking the masks: one to test their breathability, and one to test the bacterial filtration efficiency, one to test the microbial cleanliness (bioburden) and one to test the resistance to blood splashes.

In order to define both the filtering power of surgical masks and the microbial load present on the same masks, the laboratory carries out two kind of tests.

One test is a bacterial challenge test where a tool is used that allows nebulization of a bacterial suspension that comes into contact with a mask, the filtered power is defined on the basis of the number of bacterial colonies that are counted downstream of the mask. Another test is the microbial cleanliness test: an extraction liquid is used in which the templates are incubated. The extraction liquid is then filtered, and the filter positioned on plates with different types of agarized medium so as to be able to count both the number of bacterial colonies and the number of fungal colonies deriving from the masks.

The benefits of a laboratory that can characterize and evaluate the compliance of these health facilities are to guarantee an immediate response, also in the event of future emergencies, ensuring constant support and updating in normal situations. Therefore, the laboratory aspires to become a stable platform to build a self- sufficient technological, scientific and production network in the mask sector. Once the emergency is over, indeed, it will be necessary to have a laboratory for the characterization of masks and health devices which must be defined as strategic for our Country.