空气很新鲜英语

The air here is so fresh.How fresh the air is!The air is so fresh here.

fresh air这个是新鲜这个形容词修饰名词，不是固定词语，直译即可！

The air is fresh here.

fresh air 英[freʃ eə(r)] 美[frɛʃ er] n. 新鲜空气; [例句]'Let's take the baby outside,' I suggested. 'We all need some fresh air.'“我们带宝宝出去走走吧，”我提议。“我们都需要呼吸一些新鲜空气。”

名词的话是Fresh air形容词的话可以说成the air is fresh

The air is so fresh here.The air is really fresh here .How fresh the air is！或者把fresh改成clean也能表达这层意思。