I'm curious about what supplier and system you're using? I'm currently using a bunch of smartair purifier, that gets indoor pm2.5 to close to zero even when it gets really bad outside every year (also in Thailand). But considering installing a positive pressure (ducted) system with HEPA filter due to high co2 levels (tightly sealed house and no ventilation)

Curious too (also in Thailand), currently using smartair and Ikea Starkwind for PM/VOCs.

Looking to design something more integrated with CO2, house cooling, de-humidifying aspects included (controlled by HA).

Have you entertained heat exchange systems? Thoughts on the magnitude of impact to aircon?