Pong of the day

 "petrichor': the smell accompanying the first rain after a long period of warm, dry weather. 

tiny jungle (Mabozza)

See also http://en.wikipedia.org/wiki/Petrichor

and 

http://www.wordsmith.org/words/petrichor.html

My regular correspondent, a fellow Glaswegian ex-pat, known professionally as Mabozza, found the name for my remembered experience of being small and close to the ground in the days when roadside dust would have contained very little in the way of car exhaust waste, diesel or petrol.
As I remember: "When we grow up, way from the ground, we don't get the smells so much if ever. My favourite was the first summer shower releasing molecules of olfactory stuff from the pavement dust, mostly powdered leaf and earth with a hint of flowers, brambles and dead insects."