Aerosol emission produced across all activities in healthy volunteers
| Oxygen delivery | Activity | Number of measurements | Aerosol emission (APS, particles/cm3)* | Aerosol emission (OPS, particles/cm3)* |
| Nil | Breathing | 25 | 0.044 (0.022–0.08) | 0.042 (0.023–0.125) |
| Nil | Speaking | 25 | 0.088 (0.064–0.212) | 0.121 (0.075–0.237) |
| Nil | Speaking with FRSM | 23 | 0.03 (0.016–0.131) | 0.038 (0.013–0.166) |
| Nil | Cough | 25 | 1.52 (0.601–3.06) | 2.14 (0.49–4.382) |
| Nil | Cough with FRSM | 23 | 0.12 (0.06–0.555) | 0.15 (0.06–0.57) |
| HFNO (60 L/min) | Breathing | 20 | 1.861 (1.54–3.458) | 2.921 (2.127–5.044) |
| HFNO (60 L/min) | Speaking | 20 | 1.855 (1.201–2.359) | 2.571 (1.65–3.255) |
| HFNO (60 L/min) | Cough | 21 | 3.006 (2.597–5.525) | 4.25 (3.011–6.41) |
| HFNO (60 L/min) | Cough with FRSM | 10 | 0.63 (0.21–2.189) | 0.75 (0.375–1.89) |
| CPAP at 15 mm Hg | Breathing sampling at area of greatest natural leak | 20 | 0.013 (0.009–0.024) | 0.012 (0.009–0.035) |
| CPAP at 15 mm Hg | Breathing sampling at exit port | 20 | 0.002 (0–0.006) | 0 (0–0.002) |
| CPAP at 15 mm Hg | Speaking sampling at exit port | 8 | 0 (0–0.002) | 0.001 (0–0.002) |
| CPAP at 15 mm Hg | Cough sampling at exit port | 19 | 0.04 (0.01–0.06) | 0.04 (0–0.105) |
| CPAP at 15 mm Hg | Cough sampling at leak | 17 | 0.12 (0.06–0.72) | 0.21 (0–0.99) |
| CPAP at 15 mm Hg | Removing CPAP mask | 6 | 0.36 (0.195–0.57) | 0.36 (0.27–0.6) |
*This is the median IQR across individuals; average particles/cm3/s for continuous activities, peak particles/cm3 for sporadic activities.
APS, Aerodynamic Particle Sizer; FRSM, fluid-resistant surgical mask; HFNO, high-flow nasal oxygen; OPS, Optical Particle Sizer.