A syringe used for intravenous drug use lies on a table in a room on February 6, 2014 in St. Johnsbury, Vermont.

U.S. health officials have reported that overdose deaths from heroin in the U.S. nearly quadrupled between 2002 and 2013.

Large starfish on coral reef with school of small fish swimming in background

Coral that lives in hotter waters can be crossbred with coral that is threatened by global warming.

Tougher regulations ban lighting up in restaurants, offices and on public transport in Beijing.

Miami Children's Hospital pediatrician Dr. Amanda Porro, M.D administers a measles vaccination to Sophie Barquin,4, as her mother Gabrielle Barquin holds her during a visit to the Miami Children's Hospital on January 28, 2015 in Miami, Florida.

Requires most schoolchildren to be vaccinated against diseases including measles and whooping cough.

The Kennedy Space Center in Cape Canaveral Air Force Station in Florida, January 21, 2015. Anadolu Agency/Getty Images

A global movement aims to increase the discovery and tracking of asteroids 100-fold.