Chem-Trails Over the Mojave

Why can't we get information about the enormous number of "chem-trails" obscuring the sky over the Mojave desert of California?
What is the source of this pollution?
Who is doing it?
Why is it so different from con-trails?
They are very ugly?
How dangerous are they?
When they are present I experience trouble breathing through my nose and often experience throat irritation.
Why are citizens kept in ignorance.