Consider what a cloud of traffic-dust-particles look like.
Here’s is photograph of roadway dust in Santa Barbara, California.
A late afternoon sun setting behind an apartment building illuminated this frenetic cloud.
Keep in mind that traffic dust is composed of a myriad of small, large, and ultrafine shards of particulate matter, most of which is toxic. Benzene, asbestos, diesel soot, heavy metals, tire wear, crankcase and cargo drippings are some of the contaminants that either make up the dust or adhere to dust particles.