Good segment tonight on “60 minutes” about indoor air quality in offices and schools. They mentioned that the state-of-the-art Amazon office building in the story uses MERV 13 filters in the air handling system.
At the start of the COVID pandemic, I ran down to Walmart and bought the best filter they had, about $15 for a 20" x 20" MERV 17 filter – that’s almost hospital operating room quality and a significant upgrade to the 99 cent filter I’d been using. In previous years when the cherry blossom trees that line the street outside come into bloom, I’m sneezing nonstop for about six weeks. Smooth sailing after the MERV 17 filter install, it was virtually a “cure”.