I live in an apartment with windows that slide from left to right. For years, I've been installing 3M furnace filters on my windows by cutting them according to height & length to prevent pollen allergens during spring which drive my crazy. I cannot use AC for health reasons. And of course, I have a large air purifier in the apt too.
This year, before going through the DIY project which I don't mind, I want to see if it'll be simpler to use filter media if anybody sells it. I need Merv 12 or 13 and think it'll be easier to cut. I don't really get hit by any rain on my windows so the plan is to simply tape the media all across the window sill