TABLE 4

Estimates of differences to intercept (30 cm) in mean particle concentration at different distances in the measurement chamber

Event0.3 m (intercept)1.0 m1.8 m2.85 m
LFNC218.2 (168.0–268.3)22.9 (−23.1–68.8)−38.0 (−89.4–13.4)−14.6 (−79.6–50.4)
LFNC+cough400.2 (293.1–507.3)−20.3 (−84.2–43.6)−102.6 (−174.1–−31.1)*−100.9 (−191.3–−10.5)*
HFNC278.1 (219.2–337.0)−30.4 (−94.8–34.0)−34.8 (−106.8–37.2)−16.5 (−107.5–74.5)
HFNC+cough341.8 (258.6–425.0)7.1 (−53.6–67.8)−99.5 (−167.3–−31.7)*−104.0 (−189.8–−18.2)*
HFNC+M210.5 (167.2–253.9)79.1 (31.5–126.7)*14.0 (−39.2–67.2)25.0 (−42.3–92.4)
HFNC+M+cough303.4 (260.2–346.7)−31.0 (−92.2–30.2)−57.8 (−126.2–10.5)−71.3 (−159.4–16.8)
NIV222.8 (183.9–261.7)35.3 (−19.8–90.3)−30.2 (−91.7–31.3)−20.4 (−98.2–57.42)
NIV+cough228.4 (181.6–275.3)33.8 (−17.5–85.0)−43.0 (−100.3–14.2)9.7 (−62.6–82.0)

Estimates of differences in mean particle concentration (number/L) between mesh sensors at different distances from the breathing-zone of the subject based on a linear mixed-effects model. The particle concentration number includes particle sizes (0.3−10 µm). The intercept level at 30 cm is presented together with the differences (versus 30 cm) at 100 cm, 180 cm and 285 cm. 95% confidence intervals of all estimates are given in parentheses, and all differences (versus 30 cm) with a p-value <0.05 are marked with *. LFNC: low-flow nasal cannula; HFNC: high-flow nasal cannula; NIV: noninvasive positive-pressure ventilation; M=surgical mask.