On sunny days, when the outdoor temperature is suitable, open the window for ventilation (true or false?

In fact, people think that ventilation is the best ventilation time at this time, because after a night's sleep, the concentration of carbon dioxide in the house is relatively high, so it is necessary to open the window for ventilation and improve the oxygen concentration. On the other hand, the outdoor air is purified overnight, and the quality is relatively high, so this time it is most suitable to open the window for ventilation, discharge the carbon dioxide in the house and breathe the oxygen in nature, and you will feel carefree and comfortable! Of course, if there is fog or bad weather one morning, you can postpone opening the window at this time.