We have Levoit air purifiers in the kitchen and bedroom. I did research before we bought them and they seemed the best all round. I think they do make the air feel cleaner and fresher, especially if you can't or don't open windows much. You can see how much muck they filter out when you change the filters - they are black. These are not the same as ionisers, which I don't go for. They just purify the air, reduce pollution and odours. You can have them on different settings. We leave them on 24/7. They make little noise on a low setting and you get used to it, it's not annoying. In fact, I think the low background "white noise" helps me to sleep.