Table 3

Factor loadings from 24 hour averages

		Eigen value (Seattle, WA (7/93–6/94))				Eigen value (Spokane, WA (1/95–3/97))^3-151
		4.0	2.2			1.0	3.0	1.5	1.2
PM_2.5 filter measurements:
SO₄ 2–	0.24	0.95	0.06		0.13	0.89	0.19
K^3-152	0.94	0.13	−0.01		—	—	—
NH₄ ⁺	0.29	0.94	−0.08		0.26	0.85	−0.16
EC	0.92	0.27	0.02		0.74	0.06	−0.02
OC	0.94	0.17	0.19		0.82	0.20	0.07
Soil^3-153	0.08	−0.01	0.99		0.00	0.03	0.99
Carbon monoxide	0.87	0.37	0.04		0.66	0.11	−0.08
Stagnation^3-150	0.68	0.45	0.01		0.72	0.25	0.06

↵3-151 Data from Haller et al.22
↵3-152 Water soluble potassium.
↵3-153 Defined as a function of Si, Ca, Fe, Ti.23
↵3-150 Stagnation persistence index (see text).
EC = elemental carbon; OC = organic carbon.