I am driving south on a major highway. An interstate, in fact.
There are smells leaking in to the confines of the vehicle I drive. They are smells like any other.
It all comes down to context.
There is a smell I call "vaporized rubber." Its the smell of locked wheels sliding across tar pavement. Some of that black tire material becomes a vapor and gets into my nose. I have smelled the remnants of this as I pull up and survey the scene of someone's bad decisions
"Diesel urgency" is a smell that exists in many areas. Chemically, it's the smell of insufficiently burned diesel fuel. This can happen when a diesel engine is accelerating excessively (Go faster! She's fading fast!)or when one is desperately trying do decelerate(Oh Crap! Oh Crap! Oh Crap! *BANG*). It is also the smell equated with spilt diesel fuel hitting a hot surface (Get 'em out now!!).
This, too, is a smell I equate with highway calamity.
I, however, am not driving an ambulance tonight. I'm merely driving home from work. These smells leach into my nose and brain via the ventilation system of my car.
Around me, the day to day catastrophe of an interstate occurs. I am just another commuter.
The smells remind me.