> 11. Cooking pollutes the air. Opening windows for a few minutes after cooking can dramatically improve air quality. I was shocked when I got a smart air-purifier and it would send severe warnings when I was cooking. Especially in winter with windows closed for the entire day, my air quality would stay low for extended periods after cooking. Make sure you open a window for a few minutes even if it's cold outside.
Also, most central HVAC system already recirculate air (albeit quite slowly). Most residential living rooms have an ACPH (air changes per hour) of around 6-8.