2002 Almanac (page 291)  Table 5-76  Sacramento Valley Air Basin:  Annual Average Concentrations and Health Risks												

Sacramento Valley 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
Acetaldehyde	Annual Avg	1.29			1.37	1.04	0.39	1.03	1.05	0.92	1.23	0.83
	Health Risk	6			7	5	2	5	5	4	6	4
Benzene	Annual Avg	2.02	1.88	1.35	1	1.02	0.8	0.56	0.55	0.5	0.56	0.45
	Health Risk	187	174	125	92	95	74	51	51	47	52	42
"1,3-Butadiene"	Annual Avg	0.38	0.33	0.28	0.29	0.22	0.19	0.18	0.16	0.15	0.13	0.12
	Health Risk	142	125	106	108	83	70	66	60	58	48	45
Carbon Tetrachloride	Annual Avg	0.12	0.12		0.11		0.1	0.08				0.09
	Health Risk	33	32		29		26	21				25
Chromium (Hexavalent)	Annual Avg			0.17	0.14	0.13	0.18	0.11	0.1	0.1	0.1	0.1
	Health Risk			26	21	19	26	16	15	15	15	15
para-Dichlorobenzene	Annual Avg			0.11	0.1	0.2	0.14	0.11	0.14			0.1
	Health Risk			7	7	14	9	7	10			7
Formaldehyde	Annual Avg	1.57			1.77	1.75	1.91	2.76	2.92	2.52	3.61	2.51
	Health Risk	12			13	13	14	20	22	19	27	18
Methylene Chloride	Annual Avg	0.65	0.56	0.55	0.98	0.66	0.53	0.54	0.52		0.6	0.57
	Health Risk	2	2	2	3	2	2	2	2		2	2
Perchloroethylene	Annual Avg	0.07	0.07	0.06	0.05	0.17	0.05	0.06	0.05			0.06
	Health Risk	3	3	3	2	7	2	2	2			2
Diesel Particulate Matter**	Annual Avg	2.5					1.6					1.2
	Health Risk	750					480					360
Average Basin Risk***	Without Diesel PM	385	336	269	282	238	225	190	167	143	150	160
	With Diesel PM	1135					705					520

*     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."