Before Earth Day became a national holiday it was originally celebrated in Berkeley, CA in the late 1960s.
I worked there at California School for the Deaf and we were having a terrible problem with the kids getting head lice. None of us had even heard of head lice before because they didn’t exist in our area.
We tried everything we could think of, but the lice kept spreading more and more. (Now I realize that was because the children’s combs and brushes in each dormitory were all washed in the same tub of water.)
Finally one of the staff members went down to the Public Health Department and brought back a powdered substance they suggested we use.
Sure enough, it worked.
But I’ll never forget that we spent the first Earth Day putting DDT on all the children’s heads.