Mean difference (95% CI)
	Background	Coughing
Cold instruments
Total particle concentration	1.039 (0.648 to 1.461)	− 0.072 (− 0.575 to 0.431)
< 1 µm particle concentration	1.003 (0.582 to 1.455)	− 0.097 (− 0.605 to 0.411)
1–5 µm particle concentration	0.612 (0.202 to 1.046)	− 0.485 (− 1.002 to 0.032)
> 5 µm particle concentration	0.226 (-0.305 to 0.857)	0.398 (− 0.149 to 0.944)
Microdebrider
Total particle concentration	1.016 (0.718 to 1.315)	− 0.273 (− 1.029 to 0.483)
< 1 µm particle concentration	0.921 (0.544 to 1.298)	− 0.317 (− 1.076 to 0.441)
1–5 µm particle concentration	1.129 (0.294 to 1.965)	− 0.443 (− 1.248 to 0.361)
> 5 µm particle concentration	1.427 (0.597 to 2.256)	0.783 (− 0.029 to 1.596)
CO2 laser
Total particle concentration	2.065 (1.852 to 2.279)	0.822 (0.461 to 1.182)
< 1 µm particle concentration	2.091 (1.873 to 2.309)	0.867 (0.505 to 1.229)
1–5 µm particle concentration	1.591 (1.457 to 1.724)	0.245 (− 0.102 to 0.592)
> 5 µm particle concentration	0.294 (− 0.147 to 0.735)	0.341 (− 0.088 to 0.770)

Mean difference and 95% CI calculated from log-normalized values

CI confidence interval