Apologies if off-topic, but perhaps someone with HVAC experience in this arena can provide some insights off-line.

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I recently vacated my house due to mold contamination. Problems were extensive in subfloor and crawlspace. Kitchen and several bathrooms had to be gutted. Remediation is now complete, and remodeling nearing completion. House has an??American Standard AUD100R9V5K4? Ser #8235NSX1G?forced air furnace, and no cooling system (located in Colorado). The system is 100% recirc, with no humidifier. We have kept the furnace, but replaced all ducts to eliminate concern of mold spore contamination. All interior surfaces of building have been 'treated', and all personal belongings removed.?Unfortunately, we have learned that sometimes even dead mold spores can linger (clinging to surfaces, etc), and if inhaled by a sensitive occupant (that's me), can then induce recurrence of health problems.?

Question: What would be the best way to introduce high quality filtration to this system? (At this point, targets include spores, pollen, and even chemicals off-gassing from new materials).?
Obvious options would seem to include:?

- high Merv-rating filters in existing furnace
- 'sidecar' HEPA / Activated charcoal unit on the CAR (a good option, but doesn't treat 100% of the air)
- UV has fallen out of favor since we don't have a cooling coil to point it at, and not sure what other surface would be appropriate
- Electric / ionizing systems have fallen out of favor due to ozone conerns
- Could fabricate a deck in the CAR just upstream of furnace to receive a HEPA filter, and suffer the fan energy penalty in exchange for additional filtration confidence.
- Not sure what to make of stand-alone Activated Charcoal filters -- seems like they need to be discharged frequently. True?
- Another option would be to go with just the MERV filter in the furnace, then purchase mobile stand-alone HEPA / Charcoal units for main rooms of each floor. More local control, but more noise.
- Are there other options we're missing?

Note:
- We are well aware of benefits of OA in such situations, but there are complications with high smoke and ozone days in this region, so 100% will actually be desirable at times -- and night flushing is a common strategy when conditions allow. Also, the house is 115yrs old, so infiltration is significant anyway.?
- HRV would obviously come into play if we pursue an OA configuration, but when filtration requirements are added, we're concerned about complexity of system.

Has anyone gone through this type of exercise? Comments / suggestions welcome.?

Regards,

Adam