Table 2.

Studies on spatial variations of PM_2.5 components.

Location	Site	Sample No.	Organic markers (ng m−3)				Bulk species (μg m−3)
			n-alkanes	PAHs	Steranes	n-alkanoic acids	OC	EC	PM2.5 mass
Denvera	PAL (Residential)	62	30.5	2.60	1.43	223	3.03	0.31	6.51
	EDI (Residential)	59	24.9	2.85	1.52	234	3.39	0.32	6.81
	ALS (Traffic)	63	29.4	3.60	2.03	249	3.56	0.66	9.32
	MAS (Traffic)	63	24.3	3.34	1.89	233	3.51	0.48	7.79
Long Beachb,c	NLB (Traffic)	10	16.6	1.07	0.43		4.03	1.32	12.9
	SLB (Traffic)	7	17.6	1.23	0.77		3.45	0.74	11.2
	Sutter (Traffic)	10	21.6	1.65	0.58		5.07	1.70	14.6
	Riley (Residential)	10	23.5	1.48	0.62		5.09	0.92	13.6
Lower Fraser Valleyd,e	GEP (Forest)	9	10.6			60.0			2.37
	CT (Tunnel)	8	83.9			156			1.12
	SP (Urban park)	23	14.8			50.0			1.71
	SER (Urban/forest)	25	10.3			65.0			1.96
	LEL (Rural)	23	8.20			39.0			1.92
Atlantaf	Highway	7	40.1	11.0	7.97	67.7	8.16	4.06	22.7
	GeoTech. campus	7	25.1	3.19	3.15	32.0	5.53	0.96	16.4
Hong Kong, Chinag,h	PU (Traffic)	14		41.8			9.45	5.80	50.9
	KT (Industrial)	12		27.9			10.2	5.05	57.3

^aThis study.

^bKrudysz et al. (2008).

^cKrudysz et al. (2009).

^dCheng et al. (2004).

^eCheng et al. (2006).

^fLi et al. (2009).

^gHo et al. (2003).

^hGuo et al. (2003).