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In many big cities, getting a lot of dust is nearly out of your control, the only factor you can control is how often you gather it all up. I used to live practically next to a four-lane road when I was younger and even if you kept the windows closed, the dust would still creep in with every coming and going. If you ever opened a window, you'd know you'd need to vacuum soon.

Agree on dust removal. But if you have a constant source of pollutant input such as air pollution, dust or pollen, you want to be running a filter 24/7.

Large buildings don't run their HVACs in burst and then turn them off.

> Running an Air Filter 24/7 has huge diminishing returns (i.e. waste of electricity). They are best run at max fan speed for short durations instead.

I did this experiment in two locations. If I’m in the more urban area, running the air filter 24/7 was necessary.