Philip Morris International Inc. Mark Ten electronic cigarettes are displayed for sale at a gas station in Princeton, Illinois, U.S., on Wednesday, Oct. 15, 2014.

The CDC says the drop is spurred by higher prices, smoke-free policies and anti-smoking campaigns.

Industrial smoke stack emitting smog.

South Korea-based fund aims to help nations invest in clean energy and green technology.

The worldwide cost of obesity is about the same as smoking or armed conflict and greater than both alcoholism and climate change, research has suggested.

The worldwide cost of obesity is about the same as smoking or armed conflict, research suggests.

Chickens feed in a cage at a market in Sanhe, Hebei province on June 18, 2014. Five Asian countries could join China as targets for the H7N9 bird flu virus that has claimed about a hundred lives since it erupted in March 2013, scientists said on June 17.

Highly contagious strain of bird flu was discovered at a poultry farm in the Netherlands.

Corie 'Universal' Davis (C), age 33, and Alfonzo Moore, age 27, talk after a therapy session with the urban re-entry support group at the MedStar National Rehabilitation Hospital January 29, 2013 in Washington, DC.

Talk therapy is increasingly looked to as a solution over medication for preventing suicide.