Positive Matrix Factorisation (PMF) is a statistical factor analysis method, based on the law of mass conservation. By analysing measured concentrations at a series of measurement locations, the method first identifies a set of factors which can be taken to represent major emissionsources. Scores on these factors are thenregressed against the concentrations to estimate the contributions from each source.

Reference:

Soonthornnonda, P. and Christensen, E. (2008). Source apportionment of pollutants and flows of combined sewer wastewater. Water Research Volume 42, Issues 8–9, Pages 1989–1998.

https://doi.org/10.1016/j.watres.2007.11.034