Not really. Tests in a real apartment — with as many as seven people in a small room — show less than 1% change in oxygen levels in a closed room.
While oxygen levels are pretty much constant over the day, what does change is the amount of carbon dioxide in the air. Tracked by the Air Visual Node, carbon dioxide levels went from 0.08% to 0.35% — more than tripling over the course of a day! Too much carbon dioxide can be harmful.
Here are some ways to reduce the CO2 level:
1.Open your windows from time to time.
2. Leave the windows opened, just a tiny gap.
3. Get a place with a central air system.
Click here to read more: https://smartairfilters.com/en/blog/does-closing-the-windows-starve-us-of-oxygen/