I had a friend of mine recommend a book on the subject of dust ... and how this stuff just permeates our environment, into space and throughout the universe.
She gave me a strong warning about the book ... she said that once you read it, you'll never breathe comfortably again knowing that every breath you make for the rest of your life is saturated with all kinds of things from all kinds of places and that 99.99999% of the time everything is just fine but every once in a while, a tiny particle of the right type with the right content just ends up in your lungs and completely screws up your biology.