Earlier quoted context omitted.
Asbestos, lead paint, cigarettes, heroin(perscribed generously for basically whatever the doc felt like), "Radithor" (patent medicine containing radium-226 and 228, marketed as a "perpetual sunshine" energy tonic and cure for over 150 diseases), bloodletting, mercury treatments for syphilis, tobacco smoke enemas (yep that was a real thing), milk-based blood transfusions. Didn't understand those either and used the fu…
Smoking cigarettes didn’t really matter for as long as we were regularly burning wood for fuel. Turns out just burning pretty much anything and breathing in the particles is really bad for you. Makes sense we didn’t realize it was bad until we stopped burning logs and coal for home heating and cooking.
Chewing tobacco also causes mouth cancer, so there’s more to it than just inhaling byproducts of combustion.