It's not the air that's needed - it's the oxygen ! Life on Earth developed by relying on oxygen to sustain it. The 'air' could be made up of totally different components - so long as it contained about 20% oxygen.
without growth people,plants,animals and all livingthings will not grow in height ,weight .
nitrogen is essentially a building block for proteins and is need for all livingthings to grow well
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for some sciency reason
Both rely on minerals for their existence.
Cells.
Abiotic, means dead or never was alive
the sun the planets livingthings nonlivingthings water satellites
it is one kind of rays whic is very harmful and effetive for the livingthings
Air is needed for breathing photosynthesis flight carring sound and the planets weather
A cold air return is similar to a return air grille, which is needed for air to travel to the furnace to be filtered, heated OR cooled and then recirculated.
For factories to not give off smoke or fumes into the air. ... hope that is what you wanted / needed