Appendix C	Air Quality and Health Risk		Table C-25										

CONTRA COSTA - Concord - 2975 Treat Blvd - Annual Average Concentrations and Health Risks													
TAC	Conc.*/ Risk**	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2001
Acetaldehyde	Annual Avg	1.41			1.39	1.46	0.62	0.86	0.76		0.87		
	Health Risk	7			7	7	3	4	4		4		
Benzene	Annual Avg	1.84	1.58	1.41	1.13	1.08	1.09	0.48	0.56	0.57	0.57		
	Health Risk	171	147	130	105	100	101	44	52	53	53		
"1,3-Butadiene"	Annual Avg	0.315	0.265	0.253	0.305	0.232	0.242	0.149	0.176	0.192	0.155		
	Health Risk	118	100	95	114	87	91	56	66	72	58		
Carbon Tetrachloride	Annual Avg	0.13	0.125		0.108		0.102	0.082					
	Health Risk	34	33		29		27	22					
Chromium (Hexavalent)	Annual Avg				0.19	0.18	0.21	0.11	0.11		0.1		
	Health Risk				28	27	32	16	17		15		
para-Dichlorobenzene	Annual Avg			0.15	0.13	0.14	0.13	0.13	0.14				
	Health Risk			10	8	9	9	8	9				
Formaldehyde	Annual Avg	1.99			1.99	1.69	2.21	2.3	2.05		2.64		
	Health Risk	15			15	12	16	17	15		19		
Methylene Chloride	Annual Avg	0.67	0.51	0.66	0.54	0.54	0.55	0.55	0.5				
	Health Risk	2	2	2	2	2	2	2	2				
Perchloroethylene	Annual Avg	0.337	0.419	0.39	0.204	0.098	0.147	0.082	0.102				
	Health Risk	13	17	16	8	4	6	3	4				
Diesel PM	Annual Avg	No Monitoring Data Available											
	Health Risk												
Total Health Risk		360	299	253	316	248	287	172	169	125	149	0	0

*    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.													
**   Health Risk represents the number of excess cancer cases per million people based on a lifetime (70-year) exposure to the annual average concentration.  Total Health Risk represents only those compounds													
listed in this table and only those with data for that year.  There may be other significant compounds for which monitoring and/or health risk information are not available.