ABSTRACT
The response to our publication by Andrew Viner and Stewart Ayrey is much appreciated [...].
Subject(s)
Public Health , Water , Ventilators, MechanicalABSTRACT
When searching for ‘total inward leakage’ on Google, the first hit refers to a statement by the National Institute of Occupational Safety and Health [3]: “Total inward leakage (TIL) is an estimate of the performance of a respirator, which is measured as the leakage of contaminants through the filter media and through the face-seal interface and exhalation valve of respiratory protective devices under laboratory conditions. There is a lack of consensus on the most appropriate test method to measure TIL”. [...]it is not useful to discuss this with respect to its application in EN149:2001 [2]. For other tasks, good quality surgical masks provide sufficient protection. Since our paper was published, two additional systematic reviews have analyzed the current collection of studies, including the more recent studies.
ABSTRACT
BACKGROUND: During 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. METHODS: A 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. RESULTS: At 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. CONCLUSIONS: A safe, fast and very sensitive test method was developed to assess the effectiveness of RPE by comparison under controlled conditions.