Airmega 200

They don't really work if you have an active infestation. Ive got 4 lg ones in an 800sq ft house and I swear they do almost nothing. We even have this electrostatic filter in the hvac and still I've get systems when the doors close or the AC goes on. I have 2x airmega 200s, germ guardian rated for 900 sq ft, coway with uv rated for 600 sq ft. 2 upstairs and one down. If I were you id try to build the biggest Rosenthal filter or several as they don't get down hall ways or around stairs, etc. The think I don't like is they really tank your electric bill and are very noisy, as they have to stay on high mode.

The NYT just did a review and ranked the Coway Airmega 200 as the best air purifier. They're under $200. I bought two and like them a lot so far. They have an ionizer, but you can turn it off. They're quiet and move a good amount of air. There are two types -- one has a large circular front and sucks in air around the edges of the circle, and the other is a regular rectangular front that sucks air in across the entire front. I have the rectangular front model. They also have a good handle for moving it around. I really liked the Honeywell HPA300 (I think that was the model), but they stopped making them. The ones they sell now look similar but are about 1/3 bigger, and don't perform any better. I feel like the bigger model is really weak at lower levels and only works well on turbo, which is really loud, while the older models worked better at lower levels. And it's just way too big for the average room and has no handles for moving it around. I have one of those cylindrical Levoit purifiers, and it works fine but I don't like how it only sucks in air at the bottom 1/3 of the purifier. A lot of the bird dust I get (I have a grey) is floating much higher in the room.

We've been running Coway Airmega 200ms in our house basically non-stop for the last 4 years with 0 problems. Super reliable, and in line with the positive reviews we've seen online (e.g., Wirecutter). I think it makes a big difference in health too - I have fewer headaches than I used to have. We have one downstairs near the kitchen and others in each bedroom. When you clean the outer filter (easy to vacuum or rinse off) and replace the hepa filter (every 6 months or a bit longer), it is wild how much you can see that they've filtered out and I am glad not to be breathing all of that grossness in. Helps with indoor air pollution (e.g., from carpets, microplastics, dust, allergens), helps with smoke when that is a problem, and it's made us feel better when someone gets sick that we're less likely to all catch whatever they're breathing out.

Seconded - I love my coway airmega 200ms and I also have the blueair 211+ which is a bit bigger and both are awesome.

I have a Blueair 211+ for my living room and its awesome and a coway airmega for my bedroom, both are solid choices and highly rated. I do not buy name brand air filters (just amazon knockoffs) that work great.

Yes - I have used Blueair and Coway air purifiers for a long time. Blueair when I was living in the US and in China (heavier duty in China for obvious reasons). I have one in my den and bedroom and they do a phenomenal job of keeping the air dust and pollution free. Dollar for dollar the coway airmega 200m is probably the most affordable for long term cost(s) - I do not use name brand filter replacements to save, and find them to be as good as OEM filters.

Coway Air Mega's are great. Blueair's larger units are equally great - with both DO not buy their filters directly from them - way overpriced - Amazon has generic equivalents that I have been using and have performed great (have air testers in home).

If each room is 300-400 square feet, the Airmega 150 is way underpowered to get the suggested 4-6 air changes per hour. At minimum, you’d need something like the Airmega 200, but preferably something with a higher CADR so you didn’t have to run it on high 24/7. CADR is always measured at top speed, so it’s advisable to buy a more powerful unit so you can run it on a lower setting and get adequate cleaning without the noise of the top speed. Air purifiers are great, but they are not going to do anything for dust. Please read the stickied thread for more info. As others have mentioned, co2 can make basements feel very stagnant. Getting an ERV/HRV installed can bring fresh air into the space. You should also have the basement tested for radon if it’s present in your region.