Guest Posted December 6, 2021 Posted December 6, 2021 Today I purchased a roll of PM2.5 filter material from Home Pro for 469 Baht. I put some on the aircon unit in the bedroom area only. Most remains on the roll. To test this, I then started the aircon in both the lounge and bedroom areas, with the connecting door closed. The results are below. A rapid drop in PM2.5 levels in the room with the filter and a much smaller drop in the other room with no filter. The data only runs for about 20 minutes, as I needed to open the connecting door. With the connecting door open, about 3.5 hours later, the reading in both rooms is about 13. It's 25 out in the ccorridor. Of course, one of the large dedicated filters with a better quality filter mesh may do better, but I'm not going to take one of those on holiday. Quote