2×8 fireplace column with a Heat and Glo Mezzo Linear fireplace on the front side, bedroom wall behind the column.  The fireplace has a passive side heat “system”.  There are 4 open holes from the firebox (in addition to the main duct that vents through the roof) that allow heat to rise out of the sides of the firebox column via two side vents (registers) on the column.

I’m doing rockwool in all interior walls – question is do I place it on the back wall of the fireplace column?  It’s non combustible so I’m not worried about a fire risk, I’m more concerned about the exposed batts impacting air quality given the column is open to the house via the vents.

Thanks!