Just curious. I have a 38 year old house with original windows and we open the door many times per day even if we never leave the house. I am assuming we get plenty of "fresh air" circulating passively from not having an air tight house.
+1. A "tight" home (one that professionals might judge to need active ventilation, possibly using a heat recovery system) experiences natural air infiltration to the extent that less than 1/4th of the air in the home is exchanged with the outside air every hour. (Source) Most homes fall well short of this, with Estimated Natural Infiltration Rates (ENIRs) of .35 to over 1 per hour. Given the amount of outside air that comes into the average home under normal circumstances, opening the windows to get "fresh air" seems unnecessary unless there's something generating a lot of "pollution" inside (CO/H2O from a room heater, large amounts of water vapor from cooking/washing clothes/showers, etc).
I've never heard a sensible explanation for why authorities tell people to stay in their homes when air pollution levels are high--am I supposed to believe that ozone levels inside my house are materially different than outside?