When referring to music, i.e. 'popular tune', you can use the expression 'un air populaire' -> plural = 'les airs populaires'.
When referring to 'the air' / 'the sky', you can use 'les airs' (plural form) as per the expression 'par les airs' = 'by air / through the air'. It sounds far better than 'dans l'air'. See link here: cnrtl.fr/definition/airs
I hope this is helpful.
Bonne journée !