Maybe a very light coating in Liverpool, can only tell up close or at a high angle of incidence from a panel like the roof.
Here's an idea:
Everyone post the 1st portion of your Area code and how much **** is on your car.
You can pick from these levels:
1. What volcano?
2. Hard to tell even up close.
3. Need to be up close or at a high angle of incidence from the roof/bonnet/boot to tell.
4. Can clearly see there is dust from a fair distance (>15m).
5. Can see a moderate level of dust on the car, needs a clean for sure.
6. Can see a lot of dust on the car.
7. There's so much dust on the car that you can't really see the colour on the roof.
8. There's so much dust that you can't see any of the roof.
9. Complete coverage of the car, can see what car it is though.
10. Heaping piles of ash, can tell that there's probably a car there.
11. Post apocalyptic levels of dust, can't find my car.
It's like the Beaufort scale but for ash fall-out, the Biggles scale.
I'll make a map with all the results.