yes, because I haven't access to this information, but then this mass per cell variable how can be used to mitigate the dpm concentration problem? My idea could be to found it as:
Avg. particle mass in cell = (DPM conc. *mass of single particle in stream * cell volume ) / (Part resi. Time * Total particle flow rate)
But since other variables are already defined, I am not sure what can change. Maybe should I use this formula but with the 2d-cell-volume instead of cell volume? I don't know if you can answer to this qeustion, but I try.