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BackgroundDuring the SARS-CoV-2 pandemic, there was shortage of the standard respiratory protective equipment (RPE). The aim of this study was to develop a procedure to test the performance of alternative RPEs used in the care of COVID-19 patients.MethodsA laboratory-based test was developed to compare RPEs by total inward leakage (TIL). We used a crossflow nebulizer to produce a jet spray of 1-100 µm water droplets with a fluorescent marker. The RPEs were placed on a dummy head and sprayed at distances of 30 and 60 cm. The outcome was determined as the recovery of the fluorescent marker on a membrane filter placed on the mouth of the dummy head.ResultsAt 30 cm, a type IIR surgical mask gave a 17.7% lower TIL compared with an FFP2 respirator. At 60 cm, this difference was similar, with a 21.7% lower TIL for the surgical mask compared to the respirator. When adding a face shield, the TIL at 30 cm was further reduced by 9.5% for the respirator and 16.6% in the case of the surgical mask.ConclusionsA safe, fast and very sensitive test method was developed to assess the effectiveness of RPE by comparison under controlled conditions.

Original publication





International journal of environmental research and public health

Publication Date





Department for Health Evidence, Research Laboratory Molecular Epidemiology, 6500 HB Radboudumc, Nijmegen, The Netherlands.


Humans, Water, Aerosols, Masks, Respiratory Protective Devices, Ventilators, Mechanical, Occupational Exposure, Infectious Disease Transmission, Patient-to-Professional, Personal Protective Equipment, COVID-19, SARS-CoV-2