You would be surprised how much particulate certain cooking methods produce, your home can go from 0 AQI to forest fire levels for a few hours without a filter.

With the right filter and sensor, you can keep your AQI in the single digits consistently and react appropriately to particle buildup. If you have a CO2 sensor as well you can react to CO2 buildup which is something I have experienced plenty of times in a modern apartment (not necessarily dangerous levels but levels high enough that cognitive effects should be expected). It is hard to keep indoor CO2 levels anywhere near outdoor levels without forced ventilation with the outside or living in a large house.