TABLE 1

Descriptive statistics for particles measured in the breathing-zone of the test subject (30 cm from mouth)

EventMeanMinMaxMedian0.250.75Dispersion %
Particle size ≤1.0 µm
 LFNC73.021.2151.060.941.5106.5107
 LFNC+cough222.744.91167.4122.971.0248.4144
 HFNC101.215.9317.167.838.5130.0135
 HFNC+cough190.936.41444.791.961.8167.6115
 HFNC+M89.325.3230.554.841.0137.2176
 HFNC+M+cough103.129.2270.596.748.2156.5112
 NIV77.720.6245.966.433.3102.4104
 NIV+cough90.228.0263.573.839.2112.299
Particle size >1 µm and ≤5 µm
 LFNC22.17.370.218.614.824.049
 LFNC+cough47.313.7242.029.317.740.477
 HFNC42.41.8236.725.714.946.0121
 HFNC+cough41.813.3186.425.021.437.765
 HFNC+M33.57.6110.222.415.439.4107
 HFNC+M+cough27.38.480.123.417.329.150
 NIV21.65.151.822.113.326.459
 NIV+cough24.76.072.721.616.331.269
Particle size >5 µm
 LFNC1.70.55.51.20.92.1100
 LFNC+cough1.70.35.51.41.01.857
 HFNC3.60.122.81.91.23.5122
 HFNC+cough3.10.624.61.61.12.9113
 HFNC+M3.70.420.51.71.13.9167
 HFNC+M+cough2.60.89.81.91.22.988
 NIV1.30.32.51.30.91.865
 NIV+cough1.80.54.51.51.02.279

Descriptive statistics for the particle concentration (three particle size groups) measured by the breathing-zone single sensor (APS 3321) during all events. The unit used is the mean particle concentration in number per litre during the event. The dispersion of the distribution is presented as the per cent-wise ratio between the interquartile range and the median. The statistical distributions of particle counts were skewed for nearly all events and particle sizes (Shapiro–Wilk test p<0.05). LFNC: low-flow nasal cannula; HFNC: high-flow nasal cannula; NIV: noninvasive positive-pressure ventilation; M: surgical mask.