Introduction The COVID-19 pandemic has led to widespread shortages of N95 respirators and other personal protective equipment (PPE). An effective, reusable, locally-manufactured respirator can mitigate this problem. We describe the development, manufacture, and preliminary testing of an open-hardware-licensed device, the “simple silicone mask” (SSM). Methods A multidisciplinary team developed a reusable silicone half facepiece respirator over 9 prototype iterations. The manufacturing process consisted of 3D printing and silicone casting. Prototypes were assessed for comfort and breathability. Filtration was assessed by user seal checks and quantitative fit-testing according to CSA Z94.4–18. Results The respirator originally included a cartridge for holding filter material; this was modified to connect to standard heat-moisture exchange (HME) filters (N95 or greater) after the cartridge showed poor filtration performance due to flow acceleration around the filter edges, which was exacerbated by high filter resistance. All 8 HME-based iterations provided an adequate seal by user seal checks and achieved a pass rate of 87.5% (N = 8) on quantitative testing, with all failures occurring in the first iteration. The overall median fit-factor was 1662 (100 = pass). Estimated unit cost for a production run of 1000 using distributed manufacturing techniques is CAD $15 in materials and 20 minutes of labor. Conclusion Small-scale manufacturing of an effective, reusable N95 respirator during a pandemic is feasible and cost-effective. Required quantities of reusables are more predictable and less vulnerable to supply chain disruption than disposables. With further evaluation, such devices may be an alternative to disposable respirators during public health emergencies. The respirator described above is an investigational device and requires further evaluation and regulatory requirements before clinical deployment. The authors and affiliates do not endorse the use of this device at present.

The COVID-19 pandemic has led to persistent supply shortages of respiratory protective equipment in many jurisdictions. Reusable industrial respirators have been proposed and deployed as an alternative, but also face severe supply limitations. In addition, industrial respirators do not filter the user’s expired breath, a major limitation in health care settings where bidirectional protection is required. We present the development and quantitative testing of a reusable silicone respirator that can be locally manufactured using low-cost desktop infrastructure. Using standardized quantitative fit-testing (QNFT including resting and activity components according to CSA Z94.4-18) in a cohort of 41 healthcare workers (HCWs), we compared the performance of the mask to the individually-fitted disposable N95 masks that the HCWs had been assigned by our institution. Overall QNFT pass rates for disposable N95 respirators were 58.5% vs. 100% for the reusable mask. For a production run of 1000 masks, unit cost is approximately $25 CAD in materials and 35 minutes in labor per mask. The device requires further testing to assess flow resistance, carbon dioxide rebreathing, and full conformance with technical standards required for regulatory approval.

Introduction: We conducted a study using an ex-vivo porcine model to evaluate whether a thulium fiber laser (TFL) induces ocular injury in the context of inadvertent exposure to the laser beam. Methods: A 365 μm TFL was positioned at a set distance (0 cm, 5 cm, 8 cm, and 10 cm) from a freshly harvested (<12 hours) porcine eyeball and the laser was activated for one second at select laser settings for lithotripsy (0.2 J at 50 Hz, 0.5 J at 20 Hz, and 1 J at 10 Hz) and soft tissue ablation (2 J at 10 Hz, 1 J at 50 Hz). The experiment was repeated with laser safety goggles and prescription eyeglasses. Thermal injury was assessed by histopathological analysis. Results: Without eye protection, corneal injury was observed even at 10 cm away for one lithotripsy setting (1 J at 10 Hz) and both tissue ablation settings. All thermal injuries observed were superficial only, except for at 0 cm distance, where deep-layer injury was observed. Laser safety goggles offered complete protection regardless of setting or distance. Partial protection was demonstrated with prescription glasses: histopathological damage was observed for both soft tissue ablation settings and only at 0 cm for two lithotripsy settings (0.5 J at 20 Hz, 1 J at 10 Hz). Conclusions: The TFL can induce ocular injury at close distances and at higher power settings. The use of laser safety goggles confers complete protection while prescription eyeglasses confer partial protection. Further study is warranted.