Chemtrails

Also known as SLAP (Secret Large-scale Atmospheric Program), this theory alleges that water condensation trails ("contrails") from aircraft consist of chemical or biological agents, or contain a supposedly toxic mix of aluminum, strontium and barium, under secret government policies. An estimated 17% of people globally believe the theory to be true or partly true. In 2016, the Carnegie Institution for Science published the first-ever peer-reviewed study of the chemtrail theory; 76 out of 77 participating atmospheric chemists and geochemists stated that they had seen no evidence to support the chemtrail theory, or stated that chemtrail theorists rely on poor sampling.