Does your home or enclosed community have proper air production and filtering?
Plants[]
How much oxygen do the plants produce? How much carbon dioxide do they eliminate?
Pollutants[]
Do you drive combustion engine vehicles, or produce other sources of pollution? How are they dealt with?
Circulation[]
Animal lifeforms[]
Be it humans, livestock, pets, or scenery animals, you must calculate how much oxygen is being used and carbon dioxide produced.
Oxygen from water[]
It is rather simple to build something which uses electricity to split water molecules into hydrogen and oxygen.