For human life to survive you need 18-24% of the air to be breathable O2 (Earth's atmosphere has about 21% or 210,000 parts-per-million). Any less and you'll suffocate, any more and you'll get oxygen toxicity. From orbit, too little oxygen will make the atmosphere look red, too much will be yellow, and blue will be just right.
Terraforming[edit | edit source]
Oxygen requires a minimum amount of atmospheric pressure before it can begin to accumulate.
Habitability for plants and microbes to grow on a planets surface requires a ratio of 100,000 to 320,000 ppm. Habitability for animals and humans outside of a Hab building is a narrower range between 180,000 and 240,000 ppm. The oxygen range in which a world is habitable for humans is really quite narrow. You will need to pay more attention to oxygen than to the other stats when trying to keep a world habitable.
If your world's oxygen falls below 180,000 ppm, the atmosphere will look red. If it goes over 240,000 ppm, the atmosphere will look yellow. If your oxygen levels are between those points, the atmosphere will look blue.
You can't have more than 1,000,000 ppm oxygen on your world, because that's 100% of the atmosphere.
Certain biosphere genes & species can also influence your oxygen levels.
The highest oxygen percentage record of the random planets is SUFUGOL, (999,161 ppm).
Buildings[edit | edit source]
|Carbon Fixer||-Oxygen, +Pressure|
|Hydro Generator||-Oxygen, -Water|
|Kelp Farm||+Oxygen, -Pressure, +Biomass/Oxygen|
|Solar Shade||-Temperature, -Biomass/Oxygen, -Credits|
|Orbital Mirror||+Temperature, -Water, -Biomass/Oxygen|
|Biofixture Lab||-Pressure, +Biomass/Oxygen|
|AtmoGen Suite||+Pressure, +Oxygen|
|Pocket Mine||+Pressure, +Oxygen|
|Electrolysis Plant||-Water, +Oxygen|
|Comet Sling||+Water, -Biomass/Oxygen|
|Hab Complex||+Habitats, +Oxygen|
|Hab Dome||+Habitats, +Water, +Biomass/Oxygen|
|Transit Network||+Population, -Biomass/Oxygen|