Question

Claim: Chemtrails from airplanes are harmful.

Source: Kristen Meghan, Youtube // https://www.youtube.com/watch?v=4oF2pxefB9I

Answer 1

The wispy clouds that airplanes form are actually "contrails," which is short for condensation trails. The claim is false, contrails are not harmful to humans, but they are detrimental to global warming. Contrails trap heat that would typically be released into space, creating 57% of aviation's warming impact in total. The title "chemtrails" is misleading because it connotes the idea of harmful chemicals. 

Source: https://www.cnn.com/travel/article/contrails-aviation-climate-change-satavia-scn-spc-intl/index.html

https://www.sciencedirect.com/science/article/pii/S1352231020305689

https://www.faa.gov/about/office_org/headquarters_offices/apl/noise_emissions/contrails/#humans

Answer 2

Chemtrails (or contrails) are mostly just water vapor, with maybe a slight amount of engine exhaust. The reason they are so noticeable is due to the low temperatures at the plane's high altitude. These trails have no negative impact on human health. See: https://www.faa.gov/regulations_policies/policy_guidance/envir_policy/media/contrails.pdf

However, contrails are harmful to the global climate. The clouds they create trap heat reflecting up from the earth's surface, increasing atmospheric temperatures. 

See: https://acp.copernicus.org/articles/19/8163/2019/ and https://e360.yale.edu/features/how-airplane-contrails-are-helping-make-the-planet-warmer

Answer 3

"Chemtrails" don't exist. The streaks we see across the sky left by airplanes are contrails. They are created when "humid jet exhaust condenses into ice crystals in the cold, dry, high altitude air". They do not disperse chemicals capable of killing crops or mind control throughout the air.

 The EPA reports that while they do contribute to climate change, they pose no threat to people or animals. https://www.nationalgeographic.co.uk/travel/2018/02/hot-topic-should-i-worry-about-chemtrails

Answer 4

This claim as false, as chemtrails from airplanes are not harmful to humans. 

There is a conspiracy theory that these chem trails are "tranquilizing" citizens, as Jeremy Hsu from NBC News states "Despite conspiracy theories about so-called chemtrails, there's no evidence that the white plumes seen trailing from high-flying airplanes are part of a secret government program to spray toxic chemicals into the atmosphere for mass sterilization or mind control."

On the other hand, chemtrails to pose a threat to climate change. These contrails are the largest contributor to aviation's climate impact.

https://www.nbcnews.com/mach/science/do-airplane-contrails-add-climate-change-yes-problem-about-get-ncna1034521