PFAS (per- and polyfluoroalkyl substances) are toxic synthetic chemicals known to have potential health and environmental impacts. PFAS are highly resistant to degradation and are very mobile. They are also ubiquitous because of their use in common industrial products such as firefighting foams and nonstick coatings.

In the past, the assessment and management of groundwater contamination has been driven by contaminant concentrations. However, concentration data alone are sometimes not sufficient to fully understand the behaviour or effect of a plume over time.