Support Center for Regulatory Atmospheric Modeling (SCRAM)

Chemical Mass Balance (CMB) Model

The Chemical Mass Balance (CMB) Model EPA-CMB v8.2 is one of several receptor models that has been applied to air quality problems over the last two decades. Based on an effective-variance least squares method (EVLS), EPA has supported CMB as a regulatory planning tool through its approval of numerous State Implementation Plans (SIPs) which have a source apportionment component. CMB requires speciated profiles of potentially contributing sources and the corresponding ambient data from analyzed samples collected at a single receptor site. CMB is ideal for localized nonattainment problems and has proven to be a useful tool in applications where steady-state Gaussian plume models are inappropriate, as well as for confirming or adjusting emissions inventories. Guidance in their use may be found in Appendix W, Section 5.2.2 of the "Guideline on Air Quality Models (PDF)."(45 pp, 803 K, About PDF)

Chemical Mass Balance Model EPA-CMB8.2

Windows-based EPA-CMB8.2 represents the latest advancement in the CMB series and replaces CMB7. EPA-CMB8.2 has been subjected to peer review and is available for regulatory applications.

Model Code
README (PDF)(1 pg, 21 K, 2005)
README - Supplemental (PDF)(1 pg, 79 K, 2016)
Executable (ZIP)(1.1 M)
Source Code (ZIP)(4.3 M)

Model Documentation
Users Manual (PDF)(123 pp, 874 K, 2004)
CMB Protocol (PDF)(173 pp, 766 K, 2004)
Peer Review (PDF)(52 pp, 286 K, 2005)
Response to Peer Review (PDF)(6 pp, 63 K, 2005)
Model Change Bulletin (TXT)(2 K, 2005)
Presentation with Demo (PPT)(45 pp, 2.2 M) (A&WMA's 98th Annual Conference, 23 June 2005; Minneapolis, MN)

Evaluation Data Sets

Test Data Set (ZIP)(160 K)

Other Data Sets Formatted for CMB Input:

Portland Aerosol Characterization Study (PACS):
- Description/Credits (PDF)(1 pg, 9.5 K)
- Data Set (ZIP)(4.6 K)
San Joaquin Valley Fine (SJVF):
- Description/Credits (PDF)(1 pg, 10 K)
- Data Set (ZIP)(157 K)
Coastal Oxidant Assessment for Southeast Texas (COAST):
- Description/Credits (PDF)(1 pg, 10 K)
- Data Set (ZIP)(163 K)
North American Research Strategy for Tropospheric Ozone (NARSTO):
- Description/Credits (PDF)(1 pg, 9.4 K)
- NARSTO Documentation (ZIP)(2.2 M)
- Data Set (ZIP)(163 K)
Northern Front Range Air Quality Study (NFRAQS):
- Description/Credits (PDF)(1 pg, 9.8 K)
- NFRAQS Executive Summary (PDF)(15 pp, 53 K)
- Data Set (ZIP)(95 K)