ppt: Persistent Pollution Technology
Variable
Persistent pollution sector
Persistent Pollution Technology [Dmnl]
ppt = ppt + dt* pptcr

ppt in the updating graph: ( how to read )
In nodes
ppti : Initial persistent pollution technology
ppt : Persistent Pollution Technology
pptcr : persistent pollution technology change rate
Out nodes
ppgf2 : persistent pollution generation factor 2
ppt : Persistent Pollution Technology
pptcr : persistent pollution technology change rate