5 little-known things that are just deadly as smoking, according to science

Cigarette smoking, one of the least healthy habits out there, is quickly disappearing in the United States.

The rate of American adults who smoke has declined from 42% in 1965 to 15% in 2015.

However, there are a number of risk factors taking its place, many of which stem from people's growing preference for sedentary, isolated lifestyles.

As smoking makes its exit in the US, here are the risk factors science says to keep an eye on.