. Author manuscript; available in PMC: 2021 May 25.

Published in final edited form as: J Occup Environ Hyg. 2017 Nov;14(11):839–852. doi: 10.1080/15459624.2017.1335404

Table 5.

Results from statistical analysis for comparison of control performance of downflow booths

				PRR
Measurement instrument	Experimental factors	Levels	Sample size	Geometric mean	Geometric standard deviation

DustTrak	Booth size*	Short	40	161.58	1.115
		Regular	78	117.77	2.073
		Extended	76	140.92	1.501

	Supply air velocity*, m/s (fpm)	0.41 (80)	95	112.66	1.921
	Supply air velocity*, m/s (fpm)	0.51 (100)	99	160.27	1.389

	Location for powder transfer	Near	117	139.93	1.739
	Location for powder transfer	Far	77	127.52	1.685

	Use of curtains*	Yes	97	119.96	1.755
	Use of curtains*	No	97	151.61	1.642

OPS	Booth size*	Short	40	159.66	1.109
		Regular	76	124.11	1.90
		Extended	79	150.00	1.387

	Supply air velocity*, m/s (fpm)	0.41 (80)	95	125.41	1.653
	Supply air velocity*, m/s (fpm)	0.51 (100)	100	157.86	1.481

	Location for powder transfer*	Near	118	152.65	1.347
	Location for powder transfer*	Far	77	125.11	1.863

	Use of curtains*	Yes	97	130.23	1.733
	Use of curtains*	No	98	152.79	1.408

Note: Experimental factors showing statistically significant difference were marked with asterisks.