Hi, there: I'm using tracer gas to show concentration classification in a room. Here's a surface boundary condition: the concentration of tracer gas on the floor is 50mg/m3. But I can only find the way of inputig concentration on the floor with ppm. Is there any way to deal with this problem? Thank you very much.

ppm and mg/m3 have equivalence, see any conversion table for concentration units.

Thank you very much, Swarup.