Table 22.

Summary Statistics for EC and PM_2.5 Measurements at Loading Docks

Location / Compound	First Visit			Second Visit			Significant Differencea and Direction
	Observations (n)	GM (µg/m3)	GSD (µg/m3)	Observations (n)	GM (µg/m3)	GSD (µg/m3)
Philadelphia
EC	20	0.7	1.7	10	1.1	1.8
PM2.5	20	12.7	2.0	10	18.9	1.8
Columbus
EC	23	0.8	1.5	9	0.9	2.2
PM2.5	23	12.8	1.7	9	16.5	1.6
Milwaukee
EC	24	0.2	2.1	17	0.4	1.6	+a
PM2.5	24	8.8	1.9	17	11.1	1.4
Phoenix
EC	6	1.2	1.9	9	1.7	1.4
PM2.5	6	13.1	1.5	9	17.1	1.5
Portland
EC	18	0.6	1.3	10	0.8	1.5
PM2.5	18	6.5	1.4	9	6.8	1.3
Denver
EC	23	0.7	1.7	12	1.6	1.4	+a
PM2.5	23	10.6	1.5	12	8.4	1.3

^aSignificant differences (P < 0.05) in median values using Wilcoxon rank sum non-parametric comparison test. + indicates increase in GM.

Note: VOCs were not measured in the shop during the initial site visits.