Is there any validity to using activated carbon/permanganate filters to replace some or all HRV/ERV use?  Apparently the whole-house ones are effective at removing VOCs, ozone, etc and can produce air that is cleaner than the outdoor air.  Advantages are no heat or humidity loss/gain.

I was wondering about this as well. I do keep a 3M flat / fabric filter in front of the filters on our HRV, both sides to keep it balanced and change them regularly. It must keep the "core" cleaner. I had wondered about a carbon block for smells since our neighbor burns wood and if the wind is right we smell it in our house.