Forty years ago, an average of forty two percent of the popular smoked tobacco. Many of these smokers lit up while inside their homes. This put their families or roommates at risk for inhaling second hand smoke, which research shows to be a cause of lung cancer. However, over the years the number of smokers has significantly decreased, and therefore the number of smoke free homes has increased. A study done by the Center for Disease Control showed that in 2011, eighty three percent of homes were now smoke free.

Doctors attribute this drop in number to a change in social norms. Nowadays, it is frowned upon and discouraged to be a smoker. More people have more knowledge on the link between smoking and lunch cancer and are more hesitant to pick up the habit. Furthermore, smoking is prohibited in almost all social areas, like restaurants and movie theaters. This forces smokers quit their habit while at these places, which helps them quit altogether. Hopefully in years to come there will be 100 percent smoke free homes and no smokers.