Background During the ongoing COVID-19 pandemic, healthcare workers are facing shortage in personal protective equipment, especially adequate respirators. Alternative do-it-yourself respirators (ADR) emerge, without any proof of protection. Objective Verify seal potential of two ADR compared to a common FFP2 respirator. Design Quality assessment pilot study. Setting Tertiary Care Hospital. Participants Ten anaesthesiology residents. Interventions Participants performed quantitative face-fit tests (QNFT) with three respirators to evaluate seal. A common FFP2 respirator was used as baseline (control group). ADR tested in this study are an Anaesthesia Face Mask (AFM) and a full-face Modified Snorkelling Mask (MSM) with a 3D-printed connector, both in conjunction with a breathing system filter. Main outcome measures Non-inferior seal performance of ADR over FFP2, assessed by calculated QNFT based on measured individual fit factors, as defined by the Occupational Safety and Health Administration. Results For each respirator a total of 90 individual fit factor measurements were taken. Within the control group, seal failed in 37 (41%) measurements but only in 10 (11%) within the AFM group and in 6 (7%) within the MSM group (P < 0.001 respectively). However, when calculating the final, mean QNFT results, no statistically significant difference was found between respirators. Successful QNFT were determined for 5 out of 10 participants in the control group, for 8 in the AFM group (P = 0.25) and for 7 in the MSM group (P = 0.69). Conclusion Both ADR do have the potential to provide non inferior seal compared to a common FFP2 respirator. While AFM respirators are easily assembled, snorkelling masks must undergo significant but feasible modifications. Our results suggest that those ADR masks might be further investigated as they seem to be viable alternatives for situations when certified respirators are not available.

Background : During the COVID-19 pandemic, healthcare workers were facing shortage in personal protective equipment, especially adequate respirators. Alternative do-it-yourself respirators emerged, without any proof of protection. Objective : Verify seal potential of two alternative respirators compared to a common FFP2 respirator. Design : Quality assessment pilot study. Setting : Tertiary Care Hospital. Participants : Ten anaesthesiology residents. Interventions : Participants performed quantitative face-fit tests (QNFT) with three respirators to evaluate seal. A common FFP2 “duckbill” respirator was used as baseline (control group). Alternatives tested in this study were an anaesthesia face mask and a full-face modified snorkelling mask with a 3D-printed connector, both in conjunction with a breathing system filter. Main outcome : Non-inferior seal performance of the alternatives over FFP2, assessed by calculated QNFT based on measured individual fit factors, as defined by the Occupational Safety and Health Administration. Results :For each respirator a total of 90 individual fit factor measurements were taken. Within the control group, seal failed in 37 (41%) measurements but only in 10 (11%) within the anaesthesia mask group and in 6 (7%) within the snorkelling mask group (P < 0.001 respectively). However, when calculating the final, mean QNFT results, no difference was found between respirators. Successful QNFT were determined for 5 out of 10 participants in the FFP2 group, for 8 in the anaesthesia mask group (P = 0.25) and for 7 in the snorkelling mask group (P = 0.69). Conclusion : Both do-it-yourself respirators successfully pass QNFT and have the potential to provide non inferior seal compared to a common FFP2 respirator. While anaesthesia masks are easily assembled, snorkelling masks must undergo significant but feasible modifications. Our results suggest that those do-it-yourself respirators seem to be viable alternatives for situations when certified respirators are not available but need further investigation for validation. Trial registration: Clinicaltrials.gov identifier: NCT04375774 Key Points : Question: Can alternative do-it-yourself respirators protect wearers from hazardous aerosols? Findings : Our findings demonstrate that do-it-yourself respirators have the potential to provide non-inferior seal as compared to regular FFP2 personal protective equipment. Meaning : Our real-life situational testing provides evidence that do-it-yourself respirators potentially provide sufficient seal to compete with or even outperform conventional FFP2 respirators and that face-fit testing should be a mandatory safety check in healthcare providers.