Chapter 5	Air Quality and Health Risk		Table 5-65										

San Diego Air Basin Toxic Air Contaminants - Annual Average Concentrations and Health Risks													
TAC*	Conc./ Risk	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2001
Acetaldehyde	Annual Avg	1.33	1.5	1.22	1.41	1.48	0.64	1.03	1	0.86	1.04	0.84	0.95
	Health Risk	6	7	6	7	7	3	5	5	4	5	4	5
Benzene	Annual Avg	2.25	1.7	1.48	1.16	1.39	0.98	0.76	0.76	0.76	0.86	0.65	0.5
	Health Risk	208	158	137	107	129	90	71	70	70	79	60	47
"1,3-Butadiene"	Annual Avg	0.333	0.257	0.258	0.312	0.307	0.242	0.208	0.198	0.196	0.22	0.159	0.136
	Health Risk	125	97	97	117	115	91	78	75	74	83	60	51
Carbon Tetrachloride	Annual Avg	0.132	0.127		0.103		0.099	0.077				0.094	0.086
	Health Risk	35	34		27		26	20				25	23
Chromium (Hexavalent)	Annual Avg			0.24	0.19	0.16	0.18	0.11	0.11	0.1	0.1	0.1	
	Health Risk			36	28	23	27	16	16	15	15	15	
para-Dichlorobenzene	Annual Avg		0.1	0.11	0.13	0.15	0.12	0.11	0.13				0.15
	Health Risk		7	8	8	10	8	7	8				10
Formaldehyde	Annual Avg	1.64	1.53	1.26	1.76	2.25	2.13	2.62	2.62	2.27	2.67	2.23	2.59
	Health Risk	12	11	9	13	17	16	19	19	17	20	16	19
Methylene Chloride	Annual Avg	0.59	0.83	1.34	1.13	0.73	0.63	0.59	0.57		0.53	0.76	0.17
	Health Risk	2	3	5	4	3	2	2	2		2	3	1
Perchloroethylene	Annual Avg	0.282	0.269	0.263	0.2	0.207	0.249	0.147	0.125			0.089	0.061
	Health Risk	11	11	11	8	8	10	6	5			4	2
Diesel Particulate Matter**	Annual Avg	(2.9)					(1.9)					(1.4)	
	Health Risk	(870)					(570)					(420)	
Average Basin Risk***	Without Diesel PM	399	328	309	319	312	273	224	200	180	204	187	158
	With Diesel PM	(1269)					(843)					(607)	

*    Concentrations for Chromium (Hexavalent) are expressed as ng/m3 and concentrations for Diesel PM are expressed as ug/m3.  Concentrations for all other TACs are expressed as parts per billion.													
"**   Diesel PM concentration estimates are based on receptor modeling techniques, and estimates are available only for selected years."													
***  Health Risk represents the number of excess cancer cases per million people based on a lifetime (70-year) exposure to the annual average concentration.  It reflects only those compounds listed in this table													
and only those with data for that year.  There may be other significant compounds for which we do not monitor or have health risk information.  Additional information about interpreting the toxic air contaminant air													
"quality trends can be found in Chapter 1, Interpreting the Emission and Air Quality Statistics."