Parked in a parking ramp with construction going on overnight a couple days ago. After leaving and running errands noticed my car was covered in a dust like substance. Almost looks like metal flakes or something. Or kind of like sheetrock dust or concrete dust? No idea. Anyway, got a carwash, still there. It comes off with my fingernail but it's all over my car. So that would take 3.5 days to clean off. Tried a microfiber and car soap, that loosened some but not all. It clings really oddly and doesn't seem to rinse off. Any ideas how to remove it? Clay bar? Something else?