The way I do that is by using HEPA type air filters.
I was raised in a beach house that had no real semblance of any sort of modern Heating plus A/C. The beach house was heated with an oil fired boiler down in the basement. The heat was transferred through radiators sited throughout the house. But that thing cost a ton of money to run. So our primary heating plan was the wood stove. It normally did the trick although there were a few nights where the boiler had to get kicked on. Now the summers were a odd story. It could genuinely get sizzling while in the day however it always cooled off at night. That meant that every one of us didn’t even have a window cooling system in that house. The nice thing was that separate from Heating plus A/C running, the windows were always open plus the indoor air was awesome. Having fresh air in the beach house for Springtime, summer time plus fall was the best indoor air pollen levels I can remember ever experiencing. That’s a bit odd for myself and others now. Our condo is in a region where the heat is much more prevalent. That means that our condo is sealed up narrow for at least 7 weeks of the year. This means I have to be proactive about maintaining great indoor air pollen levels. The way I do that is by using HEPA type air filters. They are amazing in that they can remover more than 99 percent of all airborne air contaminants. It may not be the same sensation as having crystal clear air moving through the beach house like when I was a kid. But, it sure helps make our indoor air healthy to breathe plus that is nice with me.