Appendix C	Stanislaus County: Modesto - 14th Street Air Quality and Health Risk													Table C-39		

Annual Average Concentrations and Health Risks																
TAC	Conc.*/Risk**	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2001	2002	2003	2004
Acetaldehyde	Annual Avg										1.65					
	Health Risk										8					
Benzene	Annual Avg	2.25	1.86	1.2	1.23	1.14	1.2	0.7	0.77	0.85	0.61					
	Health Risk	208	172	111	114	105	111	65	71	78	56					
"1,3-Butadiene"	Annual Avg	0.379	0.353	0.224	0.348	0.293	0.298	0.236	0.208	0.26	0.162					
	Health Risk	142	133	84	131	110	112	89	78	98	61					
Carbon Tetrachloride	Annual Avg	0.128	0.132		0.112		0.094	0.074		0.113						
	Health Risk	34	35		30		25	20		30						
"Chromium, Hexavalent"	Annual Avg										0.1					
	Health Risk										15					
para-Dichlorobenzene	Annual Avg		0.11	0.1	0.12	0.1	0.11	0.1	0.15							
	Health Risk		7	7	8	7	7	7	10							
Formaldehyde	Annual Avg										3.09					
	Health Risk										23					
Methylene Chloride	Annual Avg	0.65	0.61	0.55	0.65	0.62	0.58	0.5	0.59	0.51						
	Health Risk	2	2	2	2	2	2	2	2	2						
Perchloroethylene	Annual Avg	0.145	0.15	0.118	0.109	0.087	0.053	0.044	0.052	0.035						
	Health Risk	6	6	5	4	3	2	2	2	1						
Diesel PM	Annual Avg	No Monitoring Data Available														
	Health Risk															
Total Health Risk 		392	355	209	289	227	259	185	163	209	163					

"*    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."																
**  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.