Air purification is important, turns out. It reduces your risk of covid and keeps your home free of dirty wildfire smoke. But you gotta install the right filters and the correct size. It pays to take a few minutes and order strong filters from Nordic Pure. From their site you can easily pick out exactly what you need, ideally MERV-14 to protect against covid and smoke. Much easier than trying to use Amazon, and it feels good to support an independent business. Reasonably priced as well. Don't even bother trying to order in late summer during wildfire season. Stock up during winter or spring!