Appendix C	Contra Costa County: Richmond - 13th Street Air Quality and Health Risk													Table C-29			

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	 	 	0.78	 	0.92	0.36	0.59	 	 	 	 	 	 	 	 	 
	Health Risk	 	 	4	 	4	2	3	 	 	 	 	 	 	 	 	 
Benzene	Annual Avg	 	1.92	1.54	1.76	1.7	1.44	1	 	 	 	 	 	 	 	 	 
	Health Risk	 	177	143	163	157	133	92	 	 	 	 	 	 	 	 	 
"1,3-Butadiene"	Annual Avg	 	0.272	0.26	0.393	0.308	0.3	0.251	 	 	 	 	 	 	 	 	 
	Health Risk	 	102	98	148	116	113	94	 	 	 	 	 	 	 	 	 
Carbon Tetrachloride	Annual Avg	 	0.123	 	0.11	 	0.097	0.078	 	 	 	 	 	 	 	 	 
	Health Risk	 	33	 	29	 	25	21	 	 	 	 	 	 	 	 	 
"Chromium, Hexavalent"	Annual Avg	 	 	0.19	 	0.15	0.26	0.13	 	 	 	 	 	 	 	 	 
	Health Risk	 	 	28	 	23	39	19	 	 	 	 	 	 	 	 	 
para-Dichlorobenzene	Annual Avg	 	0.14	0.12	0.12	0.1	0.12	0.19	 	 	 	 	 	 	 	 	 
	Health Risk	 	9	8	8	7	8	13	 	 	 	 	 	 	 	 	 
Formaldehyde	Annual Avg	 	 	1.08	 	1.32	2.22	4.27	 	 	 	 	 	 	 	 	 
	Health Risk	 	 	8	 	10	16	31	 	 	 	 	 	 	 	 	 
Methylene Chloride	Annual Avg	 	0.62	0.54	0.67	0.5	0.54	0.65	 	 	 	 	 	 	 	 	 
	Health Risk	 	2	2	2	2	2	2	 	 	 	 	 	 	 	 	 
Perchloroethylene	Annual Avg	 	0.147	0.093	0.092	0.056	0.043	0.03	 	 	 	 	 	 	 	 	 
	Health Risk	 	6	4	4	2	2	1	 	 	 	 	 	 	 	 	 
Diesel PM	Annual Avg	No Monitoring Data Available															
	Health Risk																
Total Health Risk		 	329	295	354	321	340	276	 	 	 	 	 	 	 	 	 
																	
"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 ppb."																	
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.  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.