The chemtrail conspiracy theory believers belief that long-lasting condensation trails are “chemtrails” consisting of chemical or biological agents left in the sky by high-flying aircraft, sprayed for nefarious purposes undisclosed to the general public.

Devotees to this conspiracy fear that while typical contrails dissipate rapidly, contrails that don’t contain extra substances. These extra substances are being deleivered to cause respiratory diseases and other medical issues leading to higher death rates to keep the population of the Earth down and make the Pharmaceutical companies richer.