"sweet air" is correct and usable in written English.
You can use it to describe something pleasant or fresh, for example: "The sweet air of the springtime filled the backyard with an inviting aroma."
Relief rushed through me like sweet air.
Everyone will come outside and revel in the sweet air".
As always, I was relieved to breathe the sweet air outside the hospice.
"The sweet air of the summer evening poured in through the open window," writes Wodehouse.
He escaped his captor and with an atavistic swimming motion burst upward into the sweet air.
But don't people usually leave the smelly city for the sweet air of the suburbs?
The magic ticket to asylum, and release into the sweet fresh air of American liberty, is a "reasonable fear determination".
Sounds and sweet airs that give delight and hurt not".
The isle is full of noises, Sounds, and sweet airs, that give delight and hurt not.
Sindabezi Island, "full of noises, sounds, and sweet airs, that give delight".
The isle is full of noises, Sounds and sweet airs that give delight and hurt not.
