Table 2. PM2.5 Elements Categorized by Source for All Event Types Based on Cluster Analysis and Enrichment Factorsa			
Method	Event Type		
Soil			
Anthropogenic			
Cluster analysis	dust storm and urban pollution	Mg, Ti, V, Cr, Fe, Ba, Ce	Na, Mn, Cu, Zn, As, Rb, Cd, Sb, Cs, Pb
Cluster analysis			
	industrial pollution	Ti, Ba, Ce	Na, Mg, V, Cr, Mn, Fe, Cu, Zn, As, Rb, Cd, Sb, Cs, Pb
Enrichment factor method from 			
Taylor and McLennan [1985]	all event types	Na, Mg, Al, Si, Pb, Kc, Ca, 	
Ti, Fe	Pb, V, Cr, Mn, Cu, Zn, As, Rb, Cd, Sb, Cs, Ba, Ce, Pb		
Enrichment factor method from Lide [1991]	All Event Types	Na, Mg, Al, Si, P, K, Ca, 	
Ti, V, Cr, Mn, Fe, Rbc, Ba, Ce	Kc, Cu, Zn, As, Rbc, Cd, Sb, Cs, Pb		

Final PM2.5 classification 	dust storm and urban pollution	Mg, Ald, Si, P, K, Ca, Ti, V, Cr, Fe, Ba, Ce	Na, Mn, Cu, Zn, As, Rb, Cd, Sb, Cs, Pb
Final PM2.5 classification	industrial pollution	Alb, Si, P, K, Ca, Ti, Ba, Ce	Na, Mg, V, Cr, Mn, Fe, Cu, Zn, As, Rb, Cd, Sb, Cs, Pb
aElements in bold type have a different classification depending on the type of event.			
bP is soil related during DS and IND and anthropogenic during URB.
cK and Rb are soil during DS and URB and anthropogenic during IND.
dAl is the reference soil element used in the enrichment factor method and is assumed to be from soil.