The ClearingHouse for Inventories and Emission Factors (Air CHIEF) CD-ROM gives the public and private sector users access to air emission data specific to estimating the types and quantities of pollutants that may be emitted from a wide variety of sources. Updated annually, Air CHIEF offers on one disc literally thousands of pages contained in some of EPA's most widely used and requested documents. Included are the US EPA Emission Factor and Inventory Group's most popular emission estimation tools. Included on the CD-ROM are: Compilation of Air Pollutant Emission Factors (AP-42), Fifth Edition, Volume 1, Stationary Point and Area. This contains information on over 200 stationary source categories. It includes brief descriptions of processes used, potential sources of air emissions from the processes and in many cases common methods used to control these air emissions. Methodologies for estimating the quantity of air pollutant emissions are presented in the form of Emission Factors; Sources (including Supplements A, B, C and D). These charaterizes the source categories for which emissions of a toxic substance have been identified. These volumes include general descriptions of the emitting processes, identifying potential release points and emission factors; Compilation of Air Pollutant Emission Factors (AP-42), Fifth Edition, Volume 2, Mobile Sources; AP-42 Background Files; Locating and Estimating Document Series; Emission Inventory Improvement Program Documents; Source Classification Codes (SCC)/Area and Mobile Source (AMS) Codes; NIOSH Registry of Toxic Effects of Chemicals Synonym List. Also included on Air CHIEF are the installable copies of these software programs: Chemdat 8 Factor Information REtrieval (FIRE); PC BEIS PMCALC; and Water 8. More information on these programs can be found on the NTIS Web site at, www.ntis.gov/fcpc/cpn7298.htm.