I recently got a bright 650 lumen light. When I am riding at night if one were to look down near the front of the light there are so many particles lit up in the air by the light. Is the air quality really that bad, it sure seems like cars are ruining this planet for the rest of us and we have to breath this air!

I see the same stuff in my headlamp beam when backpacking in the mountains. Clean air isn't nearly so empty as we think.

This time of year you are probably seeing a lot of pollen & dust as well

Yup, also the bugs.

Definitely the time can't come fast enough to ban all motor vehicles from polluting the air with pollen, dust, and bugs.

Hint, even in the middle of nowhere along the Allegheny River very far away from any big city and far removed from any roads, you see these same particles in the air in your headlamps

Hint, have you never seen a beam of light from the window through a darkened room revealing millions of dust particles floating in the air inside your supposively clean home?

The is an account of Denver from the 1870s, when the population waste low. The writer describes the afternoon haze that obscures the view of the mountains. It was wind- whipped dust trapped by thermal inversion.

Always has been particulates in the air and always will be. There are areas where naturally occurring asbestos creates hazardous levels in the air. The respiratory system has evolved to handle most of this via a layer of mucus that is excreted in the lungs and carried upward and out (to be swallowed) by the constant movement of the cilia lining the airways. You were likely taught this in biology or health class at one point.

https://www.soils.org/publications/sssaj/pdfs/77/6/2192

You can't see air pollution except as the color shift you get in smog.

Haven't you ever seen airborne dust when sunlight streams through a window? Same thing, cars and bikes kick up road dust, and you're shining a light through it before it settles.