Chapter 5	San Francisco Bay Area Air Quality and Health Risk										Table 5-44						

Annual Average Concentrations and Health Risks																	
TAC	Conc.1/Risk2	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2001	2002	2003	2004	2005
Acetaldehyde	Annual Avg	1.3	1.4	1.03	1.31	1.17	0.42	0.83	0.73	0.65	0.76	0.68	0.73	0.63	0.74	0.74	0.71
	Health Risk	6	7	5	6	6	2	4	4	3	4	3	4	3	4	4	3
Benzene	Annual Avg	2.18	1.82	1.49	1.49	1.4	1.26	0.71	0.61	0.71	0.6	0.56	0.425	0.454	0.439	0.372	0.314
	Health Risk	202	169	138	138	129	116	66	56	66	55	52	39	42	41	34	29
"1,3-Butadiene"	Annual Avg	0.359	0.287	0.275	0.367	0.287	0.277	0.218	0.187	0.217	0.17	0.149	0.133	0.137	0.098	0.09	0.075
	Health Risk	135	108	103	138	108	104	82	70	82	64	56	50	51	37	34	28
Carbon Tetrachloride	Annual Avg	0.128	0.125	 	0.108	 	0.1	0.078	 	 	 	0.094	0.087	0.089	0.095	 	
	Health Risk	34	33	 	29	 	26	21	 	 	 	25	23	24	25	 	
"Chromium, Hexavalent"	Annual Avg	 	 	0.23	0.2	0.19	0.25	0.13	0.12	0.1	0.1	0.12	 	0.074	0.096	0.091	0.082
	Health Risk	 	 	34	29	29	37	19	17	15	15	18	 	11	14	14	12
para-Dichlorobenzene	Annual Avg	 	0.12	0.12	0.12	0.11	0.13	0.14	0.12	 	 	0.11	0.14	0.15	0.15	0.17	0.15
	Health Risk	 	8	8	8	7	8	9	8	 	 	7	9	10	10	11	10
Formaldehyde	Annual Avg	1.87	1.73	1.43	1.56	1.66	2.06	2.62	1.85	1.76	2.09	1.77	2.32	2.57	2.22	1.71	1.32
	Health Risk	14	13	11	11	12	15	19	14	13	15	13	17	19	16	13	10
Methylene Chloride	Annual Avg	1.04	2.32	0.65	0.72	0.59	0.6	0.58	0.55	 	 	0.53	0.27	0.22	0.22	0.14	0.13
	Health Risk	4	8	2	2	2	2	2	2	 	 	2	 <1	 <1	 <1	 <1	 <1
Perchloroethylene	Annual Avg	0.204	0.232	0.169	0.128	0.082	0.094	0.067	0.071	 	 	0.078	0.059	0.052	0.039	0.035	0.029
	Health Risk	8	9	7	5	3	4	3	3	 	 	3	2	2	2	1	1
Diesel PM3	Annual Avg	(2.5)					(1.9)					(1.6)					
	Health Risk	(750)					(570)					(480)					
Average Basin Risk	w/o Diesel PM	403	355	308	366	296	314	225	174	179	153	179	144	162	149	111	93
	w/ Diesel PM	(1153)					(884)					(659)					
																	
"1  Concentrations for Hexavalent Chromium 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."																	
2  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."																	
"3  Diesel PM estimates are based on receptor modeling techniques, and the estimates are available only for selected years. Currently, the estimates are being reviewed."