Meaning of AIR in English
BAD : It's hard to find a fresh air nowadays.
GOOD : It's hard to find any fresh air nowadays.
Air (= the mixture of gases that we breathe) is an uncountable noun: 'Let's go for a walk and get some air in our lungs.'
See PURE (↑ pure )
Longman Common Errors English vocabulary. Английский словарь распространенных ошибок Longman. 2012