Why do we feel fresh air in the morning, although the photosynthesis from trees has not even started?

Question

Morning Sunlight is not enough for trees to give out oxygen.

Answer 1

lol, air is NOT pure oxygen. in fact only a fraction of the air is oxygen. even so, there would still be oxygen in the air at night, because it's not used up that quickly, or else you'd be sufficating.

Answer 2

If you live in an urban environment, you may be noticing the effects of reduced human activities during the night on local air quality in the morning... then everybody fires up their cars, more buses run, etc. and it all goes to pot.

Answer 3

what does fresh air have to do with photosynthesis?