Table 2.

Particle concentrations in laryngeal procedures and their comparison with background and coughing data

	Cold instruments	Microdebrider	CO2 laser	Reference
				Backgrounda	Coughing
Total particle concentration, particles/cm3
Median	0.012	0.024	0.438	0.000	0.036
Mean ± SD	0.708 ± 8.047	0.030 ± 0.039	0.761 ± 2.437	0.004 ± 0.011	1.601 ± 13.772
Max	119.898	0.342	36.240	0.144	195.528
Comparisons (p values)
Background	< 0.001	< 0.001	< 0.001
Coughing	0.753	0.146	< 0.001
< 1 μm particle concentration, particles/cm3
Median	0.012	0.018	0.426	0.000	0.030
Mean ± SD	0.705 ± 8.047	0.026 ± 0.039	0.742 ± 2.436	0.004 ± 0.010	1.588 ± 13.751
Max	119.898	0.342	36.240	0.144	195.510
Comparisons (p values)
Background	< 0.001	< 0.001	< 0.001
Coughing	0.686	0.152	< 0.001
1–5 μm particle concentration, particles/cm3
Median	0.000	0.000	0.012	0.000	0.006
Mean ± SD	0.002 ± 0.004	0.003 ± 0.004	0.017 ± 0.025	0.000 ± 0.002	0.012 ± 0.064
Max	0.030	0.018	0.276	0.018	1.242
Comparisons (p values)
Background	0.004	0.013	< 0.001
Coughing	0.043	0.305	0.064
> 5 μm particle concentration, particles/cm3
Median	0.000	0.000	0.000	0.000	0.000
Mean ± SD	0.001 ± 0.002	0.001 ± 0.004	0.001 ± 0.003	0.000 ± 0.001	0.001 ± 0.002
Max	0.012	0.030	0.024	0.006	0.012
Comparisons (p values)
Background	0.218	0.005	0.094
Coughing	0.174	0.089	0.131

Median, mean ± SD, and max calculated from all measured values. Measured minimum value in all laryngeal procedures and reference measurements in all size groups of particles was 0.000

SD standard deviation, Max measured maximum value

p values compared with aerosol concentrations of background were calculated using one-tailed unpaired-samples t test; for comparisons with coughing reference, two-tailed unpaired t test was used. p values < 0.05 were considered significant and presented bolded. Mean differences with 95% confidence intervals are presented in Appendix Table

ͣBackground values presented from all operation rooms where procedures took place. For each procedure type, background was tested separately according to operation room used. Reference data is presented with Italics