I've been using a dehumidifier with a hepa filter for the last 4 years or so. I mainly bought it because I moved from an inland region with about 10% humidity

I've been using a dehumidifier with a hepa filter for the last 4 years or so. I mainly bought it because I moved from an inland region with about 10% humidity to a coastal city with 40% to 60%. Things around the house didn't get dry like I was used to (dishes, shower, towels, laundry, water spills) and on top of that, occasionally had to wash ceiling when they get moldy. Thus I bought a dehumidifier. It was quite expensive at the time and I didn't at the time realize the significance of the hepa filter. I don't have any allergies. Lets just say its been running for 4 years in my place. The trick is to keep windows/doors shut and let it do its work. I move it around in the apartment - in the mornings I move it to the bedroom to get the human smell out. Later on I'll move it to the bathroom or to the spare room to dry some laundry. While all of this is happening, it sucks up all the pollen and dust, odd smells, basically most moisture (no more wet windows). Haven't had to wash a ceiling since I bought it. When you enter the apartment, it smells neutral/clear/crisp - It's kinda hard to describe the smell of clean air, but it is a distinct sensation. You still need to air out your living space every once in a while to get some "fresh" air from the outside. I'd recommend anyone/everyone give this a shot! And remember to replace your hepa filter every once in a while. If you have carpets, you'll have to do it regularly (on that note, get rid of all carpets if you can). I use a "Meaco 12L Low Energy Dehumidifier and Air Purifier". It uses about 150W of power so basically the same as running a fairly large fridge (in my country about $4 of electricity per month). There are larger models but they make more noise. You can also attach a drain pipe to the back so you don't have to empty the water container every day (useful if you aren't going to move it around).