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Emissions Modeling Clearinghouse
EMS-HAP Model Ancilliary Files

The purpose of this information is to serve as a reference for the reduction files we have posted for use with EMS-HAP version 3.0. This reference information consists of a “Readme” file that explains how we developed the emission reduction information for EMS-HAP Version 2.0, and two excel files showing the information in spreadsheet format. This information was developed for projecting the 1996 National Toxics Inventory (NTI) which is no longer available. However, because this information was the starting point for the reduction information we use for EMS-HAP version 3.0, we provide it here as a reference.


EMS-HAP version 2.0 is an emissions model that prepares annual emission inventory data for subsequent air quality modeling using either the ASPEN or ISCST3 model. The key functions it performs to prepare the inventory for these air quality models are: spatial allocation of county-level data to tracts or 1 by 1 km grids, temporal allocation of annual emissions to hourly rates, grouping and selection of inventory species into ASPEN or ISCST3 modeled species, and creation of properly formatted input files. EMS-HAP version 2.0 can also project an inventory to a future year by applying reductions based on rules developed as part of the Clean Air Act or user defined reductions, and by applying economic growth factors based on the emissions source type. The reduction information and growth factors are supplied to EMS-HAP as ancillary input files.


The README_reductions file describes the emission reduction information files provided below and details how we created them.

User-friendly Excel files discussed in the readme file:

Mact_gen_july1_02_post.xls (XLS 400K)
Mact_specific_july1_02_post.xls (XLS 460K)

| Office of Air Quality Planning & Standards | Technology Transfer Network |
| Clearinghouse for Inventories & Emissions Factors |

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