We all know about First Hand Smoke which is why we're here!
I surmise that virtually all of us know about Second Hand Smoke although I just read an article today trying to convince it's readers that SHS isn't all that bad! For every article like this I can show you 100 that say that SHS is very dangerous to humans, animals, and even plants!
But many of us don't know about Third Hand Smoke. It is the brownish sludge you've been scrubbing off your walls, mirrors, windows, and stuff in your house. Unfortunately it's virtually impossible to get out of upholstery and carpet! It's very dangerous for babies and older folks as well as pets.
Here is an article I found informative:
This is NPR quoting Dr. Norman Edelman of the American Lung Association.
Good stuff to know!