@merpreb, Hi, we haven't decided on a whole-house air purifying system as yet. We know we don't want one that is an ionizer, hydrogen-peroxide, or plasma-based because they emit some degree of ozone. Some UV-based air purifying systems produce ozone; some don't (if the bulb is coated?) – so I'm still researching this. Also, the UV-based system seems to need 2 units – one with filters and UV and a separate UV light for the coil. Some research questions the effectiveness of using the UV-based system, even if it doesn't produce ozone. The more I research, the more complicated it's becoming and more red flags (where you install it is also important, the wavelengths, etc.). I'm not sure if there is actually a whole-house air purifying system on the market that doesn't have caveats for people with lung issues and that actually will purify the air of bacteria (including NTM), viruses, mold, etc. It has to be very strong to do that and possibly the heat/AC fan has to run continuously(?), which I don't want. So, I continue to research on this topic. I'm surprised more people haven't joined in the conversation!