Norwegian Air

So I landed in Norway again, for a short 4 day visit. As with every time I come back to Norway, the very first thing I notice when I step out of the airplane is the air. It feels so fresh. I suck in extra amount of air just because it feels so nice. And every time I experience this I wonder "Is it just my imagination?" How can one actually feel the difference in air quality? Or does it have anything to do with air quality at all? Maybe it is just the particular mix of moisture in the air here.