Black powder covers interior - please help!

So I was crossing into the U.S. two days ago at Port Huron/Sarnia - great view sitting on the bridge, wonderful lake breeze with my windows and sunroof open, when a gust blows a bunch of crap off a truck who was also in line. I thought it was sand, and as I brushed it off my face I noticed that my hand was covered in a very fine black powder. Looked in the mirror and sure enough my forehead was covered too. Turns out most of my interior was covered - it is not evenly everywhere, but enough spots everywhere that if you run your hand on a surface it will sort of break down and spread.

 

When I got to my destination (Chicago) I immediately broke out a shopvac and tried to vacuum, but it was hard to see as it matches the seats perfectly. It is on the dash, side panels, all over seats and even in the back seat. After the vac, the stuff is still there: I think it is too fine to come up.

 

The powder is kind of like graphite from a pencil, or like black icing sugar - not sure what it is.

 

I am home now, so how should I start to clean? I am thinking I will take all loose items out and vacuum again, and then maybe get some slightly damp cloths and try to blot first - where ever there is a fabric spot I'll try to vacuum it up and blot again. I have some 303 Aerospace protectant and some Wolfgang leather cleaner and conditioner, but I am not sure what I should use before all that. Maybe just a damp cloth on all the hard surfaces? I am really afraid of grinding this stuff into the Alcantara.

 

Thanks,

 

Eric

I'd brush it first. Natural bristle. You may not remove it, but you'll at least spread it around enough to be insignificant. And a vac always works best when nap is raised.

Wouldn't be surprised if it's brake dust from the truck. Does the powder have any smell?