I agree that indoor combustion producing small particles that go deep into the lungs is a major problem, and there should be prevention/mitigation. But on the dust specifically, I was hoping to see a cost-benefit analysis. Since most household dust is composed of relatively large particles, they typically do not penetrate beyond the nose and throat, and so are more of an annoyance than something that threatens your life. So I am skeptical if one doesn’t have particular risk factors such as peeling lead paint or allergies, measures such as regular dusting (how frequently are you recommending?), not wearing shoes in the house, having hardwood floors if you like the benefits of carpet such as sound absorption, etc would be cost-effective when you value people’s time.

Depends on your house, air quality outside, and air quality inside but a cheap air quality monitor has shown my that an open window can clean up the air 5x faster than an air purifier.

Even during the winter or summer there is usually a small window of time (excuse the pun) that the air temp outside is about the same as your desired temp. Lots of houses have an oversized heater to account for open windows in the cold.

Window fan can expedite the process, you can get sneaky about which direction you run fans to create circulation throughout the house. Try not to create negative pressure in your house (don't blow more air out than in) especially in your basement due to radon and other bad things with negative pressure.

I try to use windows as a plan A and HEPA filters as a plan B. I recognize this is a luxury of having good air quality outside in my area.

Not all dust is created equal. You mention many types, but I would differentiate between the following two classes:

• All kinds of particles that would also be present in the ancestral environment, independent of size, such as human skin, soil material, natural fibers, pollen, and microbes adapted to these.
•  All other, mostly artificial particles, such as paint, pesticides, synthetic fibers etc., that the human immune system is not adapted to.  

While both can lead to health complications in high concentrations, I am much more worried about the latter. And if the Hygiene Hypothesis is correct, a moderate amount of the former might even be beneficial overall.

It would be useful to know relative dust levels in practice, given equipment + habits. E.g.: with such and such air filter running all the time, the air has X% less particulates of size Y; etc.

What effects does dust have on cognition? I'm pretty sure that air quality has an impact on cognition, but I'm unsure what the mechanisms of action are.

Wood flooring is generally better than carpets for controlling dust. Carpets can trap allergens like dust mites and mold spores deep within their fibers, making them harder to clean and potentially worsening indoor air quality over time.

Intuitively it seems as though dust trapped deep within carpet fibers would be unlikely to become resuspended and inhaled, and so carpet wouldn't necessarily be worse. Is there reason to believe otherwise?

There is a lot of research on mortality from household air pollution, but I wasn't able to find anything on its passive effects. I wonder how regular exposure to "normal" levels of dust affects your life expectancy.