Table 1. Best-Estimated Emission Factors (EF; Mean ± Standard Deviation) at High (10–15 ppb) and Low (<3 ppb) Ozone Levels for the Top 20 VOCs^a.

			high O3 (10–15 ppb)		low O3 (<3 ppb)
VOC signalb	empirical compound	main sourcec	R2	EF (μg/h/p)	R2	EF (μg/h/p)	EFhighO3/EFlowO3
C13H23O+	geranyl acetone	skin (S)	0.86	159 ± 15	0.88	75.3 ± 7.3	2.11
C8H15O+	6-MHO	skin (S)	0.83	337 ± 36	0.72	113 ± 18	2.98
C13H21O+	damascone, ionone	fragrance	0.77	10.5 ± 1.4	0.74	8.1 ± 1.2	1.30
C3H7O+	acetone	exhalation	0.76	1420 ± 190	0.67	1160 ± 210	1.22
C5H9+	isoprene	exhalation	0.74	307 ± 43	0.82	284 ± 35	1.08
C10H21O+	decanal	skin (F)	0.70	245 ± 38	0.57	151 ± 34	1.62
C14H29O+	C14 saturated carbonyl		0.69	12.7 ± 2.0	0.45	8.6 ± 2.5	1.48
C11H23O+	undecanal	skin (F)	0.68	41.0 ± 6.6	0.49	27.1 ± 7.1	1.51
C6H11+			0.67	221 ± 3	0.67	185 ± 34	1.19
C7H13+			0.65	77 ± 13	0.56	52 ± 12	1.47
C9H19+			0.63	10.9 ± 2.0	0.41	6.5 ± 2.0	1.68
C14H29+			0.62	3.1 ± 0.6	0.21	1.9 ± 1.0	1.57
C14H25+			0.61	5.2 ± 1.0	0.50	4.3 ± 1.1	1.23
C10H11+			0.61	3.3 ± 0.6	0.68	3.2 ± 0.6	1.03
C12H25O+	dodecanal	skin (F)	0.61	25.5 ± 4.9	0.51	19.0 ± 4.8	1.34
C12H25+			0.59	8.0 ± 1.6	0.48	6.5 ± 1.8	1.23
C9H17O+	nonenal	skin (F)	0.58	36.9 ± 7.4	0.36	20.3 ± 6.9	1.82
C9H19O+	nonanal	skin (F)	0.58	137 ± 27	0.50	92 ± 24	1.50
C7H15+			0.58	6.7 ± 1.4	0.39	5.0 ± 1.6	1.34
C16H27O+	Iso E Super	fragrance	0.56	35.0 ± 7.4	0.77	21.1 ± 3.0	1.65

^aThese VOCs were selected based on the strong correlation between their emission rates and CO₂ emission rates (indicated by R²) at 10–15 ppb ozone.

^bThe main fragmentation ions are also considered in the calculation.

^cSkin (S) represents ozonolysis of squalene in skin oil, and skin (F) represents ozonolysis of unsaturated fatty acids in skin oil.