I have been monitoring my indoor house air for two years now, and attempting to keep my air as healthy as possible. I have found that:
1) If you are lucky enough to live in an area with clean air, opening a window is orders of magnitude quicker and more effective way to clean air.
2) Gas stoves are the worst thing you can do to your house air (a fume Hood can partially mitigate this)
3) You should be weary of using any cleaning product without ventilation (open windows for a whole day)
4) HEPA filters work, but slowly. Realize you can sneeze into these things and some % of your sneeze goes right through/around the filter. They need multiple passes to fully clean the air. Big quiet HEPA filters are the way to go.
5) Activated Carbon filters grab the stuff HEPA can't but they are very slow at it, and I haven't found anything commercial that works. The thin black layer on filters doesn't work, you need something more commercial like the ones people use when they are home growing weed. IMO, the effect of these is really hard to measure and I wouldn't personally suggest this right now.
6) Humidity control is important for health and has a relationship to air particulates
All of this work and basically I open windows any nice days, when I'm cleaning, and when I cook. Many HEPA filters and a beefy carbon filter cant compete with this. Even if it means running up the heat/AC bill a bit. I'm considering some sort of heat exchanger with filters in the future, but that is overkill. I am privileged to have nice air outside though and I realize this isn't THE solution for everyone.
As far as this article goes. HEPA filters are supposed to be replaced every 6 months, but even older filters get rid of so many particulates that we KNOW are bad for you it seems worth this tradeoff. Maybe a HEPA filter with a UV light could help (not by much probably), but be weary of "24 stage filters" and all that nonsense. HEPA is all most houses really need.