What are chem-trails and are they used in the US to the detriment of health to people that live there?

Well, the jury is still out--literally, as one may join any of several class-action lawsuits on the matter--but elevated levels of aluminum, barium, and other metals in standing water does not bode well for the health of those being sprayed with these.

Chem trails are a conspiracy theory stating that long lasting trails left in the sky by high flying aircraft are actually chemical or biological agents used to control weather and harm people.