The Chemical Mass Balance (CMB) air quality model is one of several receptor models that have been applied to air resources management. Receptor models use the chemical and physical characteristics of gases and particles measured at source and receptor to both identify the presence of and to quantify source contributions to receptor concentrations. Receptor models are generally contrasted with dispersion models that use pollutant emissions rate estimates,
meteorological transport, and chemical transformation mechanisms to estimate the contribution of each source to receptor concentrations. The two types of models are complementary, with each type having strengths that compensate for the weaknesses of the other.
Chemical Mass Balance 8 is an interim step to update CMB7. Cmb8 has features that represent enhancements over CMB7. It is suggested that one consider using CMB8 for source apportionments that are suitable for CMB capabilities.