Need a good cooling filter

I’m really happy that I don’t have any animal flu symptoms or spring pollen troubles. My friend Beth had awful flu symptoms growing up, which kept my friend Beth from having pets for a long time until my friend was an adult & could find ways to deal with her symptoms. The first thing I did upon going out of my house was get an animal, because I never could at home. I’ve never had a single dust sensitivity issue or suffered from symptoms due to awful air quality. That is until I took the risk & decided to rent out basement studio loft. The basement home is incredibly cheap, not only due to the lower cost, however also because the low number of doors & windows means less heating loss. So in the winter, I almost never have to switch on my gas furnace. The underground level keeps it colder, so I don’t have to bother with A/C either. The only issue is my own dust sensitivity to mildew. Beth and I had a small flood due to a leaking spigot, & we noticed ever since I was coughing & sneezing all the time. Turns out because my landlord didn’t change out the carpet, it grew mildew! I called the guy immediately & told him he had to repair it or I was leaving. Safe to say, the guy had women out the next afternoon! But I thought that this doesn’t always keep the mold gone, so I bought an air purification system with a HEPA filter too.