Air purifier recommendations wanted?

I bought two, different sizes of these, https://www.blueair.com/us/air-purifiers  during the fires last year.  High quality, well made.  Pay attention to the recommended square footage.  

We love our Dyson Pure hot + cool. It’s a filter, space heater and fan. It also has a cool app that tracks indoor air quality and can turn on automatically if the quality drops. 

First, get rid of stuff that is making the air dirty. Get fragrance-free personal care products. Scrub and clean the mold. No new carpet or paint. Then get this air cleaner: 

https://foustco.com/

Best air purifier solution is replace your heater's filter and run the heater in fan only/no heat mode.  The $500 room air purifiers use the exact same filter as your heater but only purify the air for one room.  And if someone opens the door it's going to take hours to circulate all of the air through the room size air purifier.  The air filter in your heater will filter the air in one room in a mater of minutes. 

I bought some room-sized HEPA filters from Amazon last summer when the air was so bad from the Camp fire. We have a 100+ year old house with a lot of leaks and a kid with asthma, and the smoke was really bothering my throat and eyes too.  I got Honeywell "HPA100 True HEPA" for up to 155 sq. ft. It cost about $130.  It has two filters - a thin liner filter just behind the front enclosure that you replace every 3 months and a bigger baffle-type internal filter that is replaced every year.  I just replaced the big one and it had a LOT of stuff on it. The thinner filter which was black was light gray with dust and particles after just a couple months. I like it - it's easy to operate and simple to replace the filters, and it makes a pleasant white noise hum that you can barely hear on the lowest setting. Replacement filters are easy to order on Amazon. I have one running in my bedroom all the time and although I have no way to measure the cleanliness of the air, it feels like it's cleaner and is definitely collecting a lot of stuff from the air.

I got three Blue Pure 211+ air purifiers in the past few due to the wildlife smoke. I love them. You could really tell the difference in air quality after turning them on. 

Another vote for BlueAir. I have an old one from the 200 series. Those are built to last and mine really helped during the fires last year. Also have a small 411 model for my toddler's room. This one whines a bit even when turned off (but plugged in), but I usually have it on low setting which is very quiet.

youtube video inspired diy air purifier:  this poor man’s air purifier worked great for us in our leaky old house.  i think we spent $25 total.   you’ll need a standard box fan, duct tape and 20x20 furnace filter(s).  NOTE: filters must be rated MERV 11 or higher for the small & most dangerous smoke particles.

there are a few ways to configure this. 1) tape a single filter onto intake side of fan as you want to draw air through the filter.  2) tape two filters together then to the fan creating a triangle. then tape a triangle cardboard lid to seal the top. 3) best option is to create a three sided box with three filters (and a fourth one for the lid if you like) and tape to fan.  you’ll have a box fan box... lol.

the more filters you use, the more room it will take up in your home. but it will also be easier on the fan motor and you’ll have a more efficient air purifier.  

bulk MERV filters can be found online pretty cheap.  good to have extras on hand as the hardware stores sold out.  bulk boxes of N95 masks also helpful to share with less prepared neighbors etc.

MANY youtube videos on this technique.  some show folks testing the air before and after using one with stellar success.  works great for all types of allergies. some review they work better than expensive air purifiers as california has use/sale restrictions due to ozone in the better ones and some argue they are also the greener way to go in the not so long run. we’re stocked up for the next fire/smoke situation... sadly but realistically so.