Bob, I'm aware that the hysteria can have serious effects because people very close to me have contemplated/attempted suicide as a result of constant fear of passenger jet overflights. I've been told that a few people have committed suicide and they were also of the same community that is very paranoid over "chemtrails".
I can't directly claim that fear of chemtrails was THE cause but is quite possible to be a contributing factor that compounded on existing depression.
People who are already predisposed to paranoia for any number of reasons might just be sent over the edge by the constant belief that they have ALREADY been poisoned and that vast powers beyond their control are out to cull them in a great culling or institutionalised genocide.
A lot of people don't care if people believe stupid things and will harm themselves or others. Some do care like most of the regulars on this forum.
A few Australian chemtrail believers have been stalking Qantas pilots and attempted to accost one in Sydney airport last month. They were intercepted by police. Now a member of their group of associates has advocated shooting down a passenger plane with a heat seeking missile.
If you read the thread
https://www.metabunk.org/threads/251-Advocating-violence-against-quot-Chemtrail-quot-planes you will see that there are more than a few people advocating violent actions against commercial aircraft and pilots