Chemtrails, the conspiracy-theory name for jet-engine contrails, do not contain poison and are formed only of water and jet engine exhaust, explains HowStuffWorks. The hot, humid air spewed out by jet engines quickly condenses into water droplets and ice crystals when it meets the cold air in the upper atmosphere, creating long thin clouds behind airplanes. Contrails sometimes persist for many hours, especially in humid conditions, explains Encyclopedia.com. Contrail is short for condensation trail.
Contrails contain jet-engine by-products, such as carbon dioxide, nitrogen oxides, sulfate particles and soot, which have some negative environmental effects, states HowStuffWorks. Some people claim that the government is using contrails as a cover to release other chemicals into the atmosphere, which is why they refer to contrails as chemtrails, short for chemical trails. Some conspiracy theorists claim that the government is spraying chemicals to weed out the sick and elderly. Others believe that the government is attempting to fight climate change with contrails, whereas in truth, jet-engine exhaust contains climate-change-causing greenhouse gases.
The Environmental Protection Agency, the U.S. Air Force and NASA all refute chemtrail conspiracy theories, dating back at least as far as 2001, reports USA Today. Conspiracy theorists believe the EPA, Air Force and NASA are all part of a chemtrail conspiracy. One quoted NASA scientist stated that conspiracy theorists do not have a good grasp of logic.