Conspiracy theories can be stubborn, particularly in the echo chamber of the internet.

One persistent belief in some quarters is that the government — or business, perhaps — is deploying a fleet of jet aircraft to spray chemicals into the sky to control the population, food supply or other things.

As evidence, they point to what they call “chemtrails,” which are more commonly known as contrails, or condensation trails, produced at high altitudes as water vapor in jet engine exhaust condenses and freezes.

Adding fuel to the chemtrails theory is the fact that there are a few legitimate reasons for atmospheric spraying — “seeding” clouds to make rain, for example — and in recent years there has been some research on the idea of spraying chemicals as a potential way to fight global warming.

But now, scientists have become more organized in their efforts to shoot down the idea, conducting a peer-reviewed study in Environmental Research Letters that debunks chemtrails supporters’ claims.