Appendix C	Butte County: Chico-Manzanita Avenue Air Quality and Health Risk										Table C-41			

Annual Average Concentrations and Health Risks														
TAC	Conc.*/Risk**	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2001	2002
Acetaldehyde	Annual Avg				1.55	1.11	0.54	1.15	1.17	0.96	1.41	0.89	1.10	1.33
	Health Risk				8	5	3	6	6	5	7	4	5	6
Benzene	Annual Avg				1.10	1.14	0.85	0.67		0.55	0.64	0.52	0.50	0.54
	Health Risk				102	106	78	62		51	59	48	46	50
"1,3-Butadiene"	Annual Avg				0.30	0.25	0.21	0.22		0.17	0.15	0.14	0.16	0.15
	Health Risk				111	94	77	81		64	56	54	59	58
Carbon Tetrachloride	Annual Avg				0.11		0.10	0.08					0.09	0.09
	Health Risk				29		26	21					23	23
"Chromium, Hexavalent"	Annual Avg				0.15	0.13	0.16	0.10	0.10	0.10	0.10	0.10	0.10	0.06
	Health Risk				23	19	24	16	15	15	15	15	15	9
para-Dichlorobenzene	Annual Avg				0.10	0.13	0.10	0.12					0.13	0.15
	Health Risk				7	8	7	8					9	10
Formaldehyde	Annual Avg				2.08	1.78	2.04	2.99	3.42	2.63	4.15	2.76	3.25	4.47
	Health Risk				15	13	15	22	25	19	31	20	24	33
Methylene Chloride	Annual Avg				0.81	0.50	0.53	0.58					0.36	0.09
	Health Risk				3	2	2	2					1	0
Perchloroethylene	Annual Avg				0.06	0.27	0.05	0.05					0.02	0.02
	Health Risk				2	11	2	2					0.9	1
Diesel PM	Annual Avg	No Monitoring Data Available												
	Health Risk													
Total Health Risk					300	258	234	220	46	154	168	141	183	190

"*    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.