Including viable-to-RNA ratio (f_inf) at the level of the emission rate
... and hence in the concentration, rather than only in the exposure.
Some tests had to be modified, multiplying values (concentrations or emission rate) by typically 0.5, or 0.305 (mean of uniform distribution of the viable-to-RNA factor when varying from 0.01 to 0.6).
This solves #364 (closed)