Estimates of change in particle concentrations over time
| Event | Fixed estimate | Lower 95% CI | Upper 95% CI | Intercept | p-value |
| Particle size ≤1.0 µm | |||||
| LFNC | 0.1 | −0.5 | 0.7 | 72.4 | 0.721 |
| LFNC+cough | 27.3 | −4.0 | 58.6 | 72.5 | 0.087 |
| HFNC | −2.5 | −6.7 | 1.7 | 115.1 | 0.238 |
| HFNC+cough | 25.7 | −16.6 | 68.1 | 49.4 | 0.232 |
| HFNC+M | −0.2 | −2.2 | 1.9 | 90.3 | 0.862 |
| HFNC+M+cough | 4.4 | −0.3 | 9.0 | 79.0 | 0.065 |
| NIV | −0.1 | −0.7 | 0.5 | 78.2 | 0.743 |
| NIV+cough | 3.6 | −0.1 | 7.4 | 70.2 | 0.059 |
| Particle size >1 µm and ≤5 µm | |||||
| LFNC | −0.8 | −1.2 | −0.5 | 26.7 | <0.001 |
| LFNC+cough | 2.4 | −4.2 | 8.9 | 34.2 | 0.474 |
| HFNC | −5.8 | −13.2 | 1.5 | 74.5 | 0.120 |
| HFNC+cough | −1.2 | −8.7 | 6.3 | 48.5 | 0.750 |
| HFNC+M | −2.6 | −7.0 | 1.7 | 48.0 | 0.235 |
| HFNC+M+cough | −1.5 | −2.9 | 0.0 | 35.4 | 0.049 |
| NIV | −1.2 | −1.9 | −0.4 | 28.2 | 0.002 |
| NIV+cough | 0.1 | −1.9 | 2.1 | 24.2 | 0.929 |
| Particle size >5 µm | |||||
| LFNC | −0.1 | −0.2 | 0.0 | 2.4 | 0.009 |
| LFNC+cough | −0.2 | −0.3 | −0.1 | 2.7 | 0.005 |
| HFNC | −0.6 | −1.3 | 0.1 | 6.7 | 0.095 |
| HFNC+cough | −0.6 | −1.5 | 0.3 | 6.4 | 0.180 |
| HFNC+M | −0.3 | −1.1 | 0.5 | 5.4 | 0.440 |
| HFNC+M+cough | −0.3 | −0.5 | −0.2 | 4.5 | <0.001 |
| NIV | −0.2 | −0.3 | −0.1 | 2.5 | <0.001 |
| NIV+cough | −0.1 | −0.2 | 0.0 | 2.3 | 0.084 |
Estimates of change in particle concentration (number/litre) per minute near the breathing-zone of the subjects for all events, based on measurements from the breathing-zone single sensor (APS 3321). Results from three particle size groups are shown. LFNC: low-flow nasal cannula; HFNC: high-flow nasal cannula; NIV: noninvasive positive-pressure ventilation; M: surgical mask.