On Monday night, 17-year-old reality TV star (and apparent conspiracy theorist) Kylie Jenner tweeted a typo-ridden meme about airplane condensation trails. It's worth quoting the post in full:
For the record: No, Kylie Jenner, you do not need to be afraid of "chemtrails" — the term commonly used by conspiracy theorists to refer to the condensation trails that come from planes.
Condensation trails, or "contrails," are a byproduct of airplanes — formed naturally when the warm air that comes from a plane's engine mixes with the cold temperatures of the upper atmosphere. Conspiracy theorists argue that the government is using contrails as a cover to spread chemicals across the country, with a wide array of alleged effects (most commonly, controlling the weather and making people sick).
None of this has any basis in reality, but if you'd like some reassurance, here's a document from the Environmental Protection Agency explaining why contrails "pose no threat to public health." Here's a similar document from the Air Force. If you'd rather not take a federal agency at its word, Gawker's independent weather blog The Vane is one of many sources — including scientific journals, universities, and and major media organizations — to feature a thorough, scientific debunking of the conspiracy theory. You can read it here.
The one caveat, cited by many who have investigated the conspiracy theory, including the EPA: contrails may contribute to human-induced climate change. So Kylie, if you're really worried about it, maybe cut down on all that private plane travel?