Scientists from the Department of Aerosol Chemistry and Physics have long been dealing with, among other expertise, size-resolved measurements of the penetration of aerosol particles through various materials. This activity has now found application in the fight against the coronavirus pandemic (COVID-19), and our scientists have been measuring the filtering efficiencies of various types of PPE (Personal Protective Equipment) practically since the beginning of March. These measurements are based on requirements of various institutions, such as the City Hall, which are interested in the effectiveness of the purchased protective equipment. However, there are also universities or private companies that are engaged in the development of new filter materials or entire pieces of personal protective equipment. Last but not least, we are approached by a number of ordinary citizens who are trying to contribute to mitigating the effects of the pandemic on their own.
The Department of Chemistry and Physics of Aerosols performs two types of measurements as part of testing the filtration efficiency of PPE:
– Standardized test of size-resolved filtration efficiency of the material sample of a given PPE in the range of 20 – 400 nm. The resulting data show the information on how the material itself captures different particle sizes. This is a very robust method of testing the functionality of the material itself. In this case, a thorough sealing of the sample is ensured. This means that all challenging aerosol particles pass only through the test material. Part of this measurement is also monitoring the pressure drop over the material (in other words the breathing resistance).
– Test of the entire PPE (surgical drape/respirator/half mask) on a test manikin head. Again, the measurement of the size-resolved filtration efficiency of the given PPE takes place in the range of about 20 – 600 nm. As part of this measurement, a test of the given PPE fastened by the supplied fastening means (cords, rubber bands, etc.) is first performed. And, as a second test, the measurement is performed with the facepiece of the PPE sealed with adhesive tape to prevent the penetration of challenging aerosol particles around the facepiece of the PPE. This test is not as robust and repeatable as the test of the material itself, and it depends how well the PPE is attached to the manikin’s head and then eventually sealed with the tape. This test is performed using instrumentation borrowed for the purpose of testing of PPE from National Institute for Nuclear, Chemical and Biological Protection.
J.O. in the morning broadcast of Studio 6:
2.9. 2020 Jakub Ondráček appeared in the morning broadcast of the Czech Television as part of Studio 6 (ČT24) with a contribution on the effectiveness of various types of personal protective equipment, sealing of face masks and individual methods of virus transmission (aerosol, surfaces, etc.):