Here it smells damp. Not soggy-dog damp, but kinda cold damp. It's as though the small change in ambient temerature between the sunny bits and the shady bits is enough to literally squeeze molecules of water out of the air and up your nose.
I noticed this for the first time a couple of days ago when I was riding along on my motorcycle. The highway I was travelling along splits into a double decker section for a while, and I just happened to be on the lower level. Anyway, that's when I noticed it.
Just thought I'd mention this. Use it, don't use it. Whatever.