Any MERV8 or higher filter will work. You don't need a HEPA filter. HEPA is only useful when you can only pass the air through the filter once, like in hospit

Any MERV8 or higher filter will work. You don't need a HEPA filter. HEPA is only useful when you can only pass the air through the filter once, like in hospitals. A home air filter can push the air through the filter several times, so an MERV8 is just as good as a HEPA and lasts longer. I used a DIY filter to remove wildfire smoke from my apartment. It's just a 12"x12" MERV8 filter taped to the front of a small fan. It worked well. I periodically opened my windows to exchange the stuffy air with fresh+smokey air. After closing the windows, the filter took about 30 minutes to remove all of the smoke inside.