I don’t know enough about it to say, really. That’s the thing where airplanes don’t have condensation trails, but whenever you see clouds behind one they are crop dusting chemicals on people? You’d think by now someone who works on airplanes would have noticed the chemical tanks/sprayers, or sampled where the contrails landed for unexpected chemicals.

Someone who believes in it with just a bit of money could surely fly up and sample the air inside of one of the trails, for example.