TABLE 1

Aerosol particle concentrations of different sizes during conventional nasal cannula therapy and high-flow nasal cannula (HFNC) therapy with and without a mask

Particle size	Conventional nasal cannula^# versus HFNC (n=5)						*HFNC with versus* without a mask (n=6)**
	Concentration at 1 foot^¶			Concentration at 3 feet^¶			Concentration at 1 foot^¶			Concentration at 3 feet^¶
	Conventional cannula	HFNC	p-value	Conventional cannula	HFNC	p-value	No mask	Mask	p-value	No mask	Mask	p-value
≤0.3 µm	710 212±622 173	581 273± 513 067	0.138	743 822±658 053	570 318± 490 647	0.043	706 247± 510 591	706 611± 531 585	0.753	653 710± 460 070	633 964± 439 677	0.249
0.3–0.5 µm	29 598±25 464	22 914± 18 332	0.686	36 511±32 609	24 666± 20 414	0.08	23 020± 17 297	21 911± 17 796	0.046	23 275± 18 722	21 802± 17 307	0.173
0.5–1 µm	2821±1464	2744±1317	0.50	3966±2758	2593±1243	0.043	2575±1124	1980±1083	0.028	2380±1118	2053±1082	0.173
1–3 µm	913±368	876±436	0.345	943±499	732±316	0.043	758±348	544±274	0.028	647±295	501±252	0.028
3–5 µm	436±166	418±242	0.50	423±200	355±179	0.08	386±225	266±117	0.028	319±171	254±124	0.116
5–10 µm	205±77	194±127	0.50	152±86	142±80	0.225	197±177	129±65	0.173	135±114	107±58	0.753

Data are presented as mean±sd. ^#: conventional nasal cannula therapy was performed at 10–15 L·min⁻¹; ^¶: values are indicated in particles per cubic foot. 1 foot=30.5 cm.