Very good for room of around 50 metre square (even though it claims to handle over 70 m2). Begin to struggle for bigger room. Most days it did suck up pm2.5 particles when reading is not too high in the air. Used it during Australian bush fire 2019-20 when pm2.5 reached above 800, the filter reduced reading down to below 200. Impressive. But make sure room not too big.