The phrase 'in open air' is correct and can be used in written English.
For example, you could use it in a sentence such as: "We decided to have the party in open air under the stars."
More important, Steinmetz believes that he is able to get superior pictures flying in open air.
"Women come here to be burqa-free in open air," said Ms. Begum, "but also to exercise.
This is a visual statement from an artist insisting that landscapes must be done in open air.
Countries burning their waste in open air and some factories will have to find alternative techniques, Mr. Buccini said.
Herbs that lose their scent in open air, such as saffron and cardamom, are kept in closed containers.
His feisty work presents a bracing contrast to the pantheistic refinement of the drawings in "Open Air Sketching".
Accountants and lawyers share trestle tables in open-air offices.
She focused on acting and appeared in open-air Shakespeare plays in Regent's Park.
Guests sleep in one of seven bunk beds and wash in open-air showers.
It filled quickly, with patients sleeping in open-air corridors that have been covered with tarpaulins.
These items sold briskly to low-end retailers and in open-air markets throughout the world.
