We just bought a house and the return air grill for the forced air furnace is within ten feet of this fireplace. I was told this application can create a negative pressure within this room when the fireplace and furnace are used together. This negative pressure may pull dangerous gases from the fireplace into the living area.

What can I do to prevent this from happening?

Find a grill in which the grill is facing the opposite way instead of down?

I may not be able to relocated the intake grill.