I think you are misinformed.

"We have not seen any credible evidence that chemtrails exist. If we did see any evidence that governments were endangering their own citizens in the manner alleged in the chemtrails conspiracy, we would be eager to expose and stop any such activities." (https://keith.seas.harvard.edu/chemtrails-conspiracy-theory)

And I am always wondering, who is this entity "they" that you refer to?