[preciousjeni]

There have been campaigns since the late 1800s to stop the sale of tobacco. Lung diseased was known to be caused by smoking as early as the 1920s. Anti-smoking campaigns didn't become remarkably successful until the 1980s when there were finally decades of scientific research to back up the claims and sufficient funding to make a splash.

But, claims that people didn't know smoking was harmful early in the 20th century are completely unfounded. It just depended on which sources people listened to...the advertising of tobacco companies or the warnings for the medical community.