Toxic Air Contaminant	Unit Risk/Million People*
Acetaldehyde	2.7
Benzene	29
"1,3-Butadiene"	170
Carbon Tetrachloride	42
Chromium (Hexavalent)	"150,000"
para-Dichlorobenzene	11
Formaldehyde	6
Methylene Chloride	1
Perchloroethylene	5.9
Diesel Particulate Matter	300**

*  The Unit Risk represents the number of excess cancers per million people per	
microgram per cubic meter TAC concentration over a 70-year lifetime exposure.	
** A diesel particulate matter unit risk value of 300 is used as a reasonable estimate	
"in the ""Proposed Risk Reduction Plan for Diesel-Fueled Engines and Vehicles"""	
"(ARB, July 13, 2000)."