It’s great that PPS can reduce PM2.5 and CO2 to extremely low levels. I live in an area with industrial pollution (coal etc) and am concerned about VOCs, NOXs, SO2s etc as well. Wouldn’t I bring in more of those if I constantly bring in outside air even when the pollution is high outside? Unfortunately I haven’t been able to exactly identify the chemical that’s causing issues for me yet. I’d love to hear your thoughts on this situation.