Source Classification Codes
The Source Classification Codes are eight or ten digit codes that the EPA uses to classify different types of activities that generate emissions. An SCC represents a unique source category-specific process or function that emits air pollutants. An SCC is used as a primary identifying data element in the National Emissions Inventory as well as other EPA, State, Local, and Tribal air quality systems and databases. The following are examples of processes described by SCCs and the emissions they may produce:
- Burning fuel in a boiler produces oxides of nitrogen (NOx) and other criteria and hazardous air pollutants.
- An industrial process such as paint coating produces volatile organic compounds (VOCs)
- Fire produces particulate matter (PM)
In general, SCCs use a hierarchical system in which the classification of the emissions process becomes increasingly more specific with each of the four levels (starting on the left of the code and moving from left to right). The first level of description provides the most general information about the emissions process. The fourth level is the most detailed and describes specifics about emissions process. Over time the evolution of emissions activity and regulations where SCCs were needed, as well as other factors, have led to a concurrent evolution of the SCCs structure. Some SCCs have been retired, others have been created, and others have been modified or converted. For example, some general SCCs that included a broad range of processes have been retired and new SCCs have been created to identify more specific emissions processes. Some SCCs were created for specific regulations. SCCs are not specific to a pollutant, so that one SCC can describe a process that emits more than one pollutant.
Within the Reporting Code table Gateway users may access a list of all the Source Classification Codes (SCCs), available in the Emissions Inventory System. The Source Classification Codes are classified by data categories: Point, Nonpoint, Events, Nonroad, and Onroadsources. The Gateway Source Classification Code List on the Gateway provides a table of all active and retired SCCs listed by Data Category.
Definitions of the fields that are displayed in the data table are provided below:
Data Category: Refers to whether the SCC source is Point, Nonpoint, Nonroad, Onroad, or Event. Some retired codes included a Biogenics data category but these are now considered Nonpoint
Code: The 8 or 10 digit SCC code.
SCC Levels 1-4: Hierarchial code level descriptions of the processes. The level of detail increases as the SCC level increases.
Map To: In some cases a code is retired or modified and a new code should be used in its place. This field shows which code should now be used. For example, SCC 10200210 was retired in 2008 and has a map to code of 10200205 which is the code that should now be used instead of 10200210.
Last Inventory Year: Refers to the last year the code was valid. If the cell is empty it means the code is still active. For example, if a cell contains "2002" then that code was used in 2002 but was no longer considered active in future year inventories.
Option Group: For internal EPA use. Refers to a group of SCCs that may overlap (parent and children SCCs).
Option Set: For internal EPA use. Refers to the hierarchy of SCCs within an option group.
Sector: Sectors can be used to summarize emissions allocating emissions to different categories with multi-pollutant inventories in mind and are especially helpful for summarizing combinations of CAPs (criteria air pollutants) and HAPs (hazardous air pollutants). The EIS Sectors can also be further aggregated to provide custom summaries.
ERT Valid: Refers to use in the Electronic Reporting Tool (ERT). This field is currently being used to identify which SCCs are used by SPPD for their regulatory purposes.
Short Name: This is an abbreviated description of the code for quick reference.
Usage Notes: Details of how to use an SCC where applicable.
Last Updated Date: Refers to the date when this code was last updated in some way. For example, code 10500102 has a last inventory year of 2008, effectively retiring this code for 2011 and 2014 inventories.
Tier 1-3 Name: For internal EPA use. These are numerical codes associated with Tier 1-3 descriptions. They are helpful when compiling emissions data by tier descriptions.
Tier 1-3 Descriptions: For internal EPA use. These are high level categories of SCCs used to summarize CAP emissions trends in EPA documents. Tier 1 is the most general and tier 3 the most detailed. These categories are broader than level descriptions. While they were created for EPA use, some SLTs find this way of grouping SCCs helpful.
Activity Value Required?: For internal EPA use.
Source Classification Code List
Source Classification Code Information
Clicking on the SCC in the data table will take you to the Source Classification Information page for that SCC record. There are two tabs, SCC Detail and QA Threshold you may select. The page defaults to the SCC Detail tab displaying the details for the particular SCC with all the same fields listed as in the Source Classification Code List table.
Source Classification Code Detail
Emissions QA Values
Clicking on the QA Threshold displays the pollutant codes, pollutant descriptions and the QA threshold values for each pollutant for that SCC.
