The Atmosphere and Lifeforms
Earth's atmosphere, often called air, was essential to human life, and all other Earthly life, for without it, breathing would have been impossible. When Spaceships were built, they were built in such a way that they could contain the atmosphere inside that they brought from Earth or whatever world they came from.
The atmospheres of the planets known as Solar Terrarium and Balunia were heavily polluted. On Solar Terrarium, much of the sunlight was blocked and the planet became much cooler, and Balunia was completely uninhabitable. However, Solar Terrarium's atmosphere was cleaned up by the Superfriends, allowing the natives to come out of their homes, and a family of Balunians came to Earth to live out the rest of their days.