Fig. 1 Low-cost custom-built heated humidifier More

Fig. 2 Labeled experimental set up More

Fig. 3 Bubble CPAP setup with: ( a ) no humidifier (control) ( b ) passive bubbling humidifier ( c ) low-cost custom-built heated humidifier, and ( d ) Fisher Paykel heated humidifier More

Fig. 4 Relative humidity delivered to the simulated patient lung with each humidification setup as flowrate varies from 4 to 8 LPM More

Fig. 5 Temperature delivered to the simulated patient lung with each humidification setup as flowrate varies from 4 to 8 LPM. More

Fig. 1 Containment and filtration intervention evaluated during the two sets of experiments: the containment pod with HEPA-filtered extraction systems ( a ) CP-HEPA-1 and ( b ) CP-HEPA-2 More

Fig. 2 Ambulance layout is shown. The containment pod with HEPA extraction systems (CP-HEPA-1 or CP-HEPA-2) is displayed. The auxiliary HEPA is permanently built into the ambulance patient module and was present in both layouts. The ambulance HVAC system is represented as a fan in the upper left o... More

Fig. 3 Single-line diagrams of the experimental conditions: ( a ) baseline, and ( b ) CP-HEPA-1 or CP-HEPA-2. The airflow is represented by solid arrows and the particles are counted by the four OPCs at a sample volume of 1.2 L/min. More

Fig. 4 The 5-point moving average of the raw data from the three experiments is shown in particles/L versus time: ( a ) baseline, ( b ) CP-HEPA-1, and ( c ) CP-HEPA-2. The different phases can be observed: phase 1 (auxiliary HEPA), phase 2 (stabilization), phase 3 (aerosol generation), and phase 4... More

Fig. 5 Average particle concentration in particles/L during the aerosol generation and decay phases for the baseline, CP-HEPA-1, and CP-HEPA-2. One-way ANOVA was performed. Statistical differences are shown with an asterisk ( p  < 0.001); ( n  = 6). More

Fig. 1 ( a ) Rendered 3D model of a custom frame and ( b ) fabricated custom frame with silicone mold around the contact area More

Fig. 2 ( a ) Wearing a custom mask frame with the right fit and ( b ) wearing a disposable surgical mask over the custom mask frame to improve the seal. The mask is kept in place by a rubber band. More

Fig. 3 Evaluations of the effectiveness of the airtight seal with the custom mask frame ( a ) Evaluating airtight seal using the respirator fit test kit (qualitative test), and ( b ) Examining a thermal image of air temperature around the edges or contact regions of the mask (quantitative test) More

Fig. 4 Thermal images captured when the subject was inhaling (left) and exhaling (right), while wearing a disposable surgical mask with (bottom) and without (top) the custom frame More