Review on 🌬️ Smartmi Large Room HEPA Air Purifiers for Home Bedroom - Alexa Compatible, H13 True HEPA Filter, Eliminates Odor, Pet Dander, Smoke, Dust, TVOC, Pollen, PM2.5 - Smart & Quiet Air Cleaner with Voice and Gesture Control by Monica Harris

The sound of the engine is constantly changing and seems to struggle and/or howl. Also, the speed can only be changed through the app. I like it and my nose felt less stuffy after sleeping in a room with it the first night, but within a day or two it seemed to stop filtering. But the fan noise keeps changing and whining, and it's a bit annoying. Also, the display only shows C. I wish the US would go to C like the rest of the world, but we're still on F, so not being able to change that is a little frustrating. On day 3 he randomly jumped from no VOC to high VOC and then jumped back. There weren't any changes, so that was weird too. Update, after a few days the filter seemed to stop working. If I put an old different brand filter that I had in the basement in the room I can sleep and breathe again, if I take it off and use that the filter effect seems to be gone. The company tried to help until the 30 day return window was over and then nothing. Revain will not accept returns without a 20% restocking fee.