I've got two Blueair 121s (the larger sibling to the 211+) that were recently on sale at Costco.com for the price of the 211+. My family could sense the differe

I've got two Blueair 121s (the larger sibling to the 211+) that were recently on sale at Costco.com for the price of the 211+. My family could sense the difference in air quality within a couple hours. I can't say that about any of the prior purifiers we've tried.