and 0.1 for homes with central AC with high efficiency in-duct air cleaner. Median modeled 24-h average indoor concentrations of PM 2.5 of outdoor origin for those three configurations were 8.4, ...

As Outside’s outdoor ... Filtrete 2200 20x20x1 air filters. (Photo: Stuart Palley) One box fan (preferably 20 inches) Four PM2.5 air filters (preferably 20×20 inches) Duct Tape Knife Cardboard ...