In this November 28, 1966 file photo, one of the 10 beagles involved in the first test of the Veterans Administration Hospital in East Orange, N.J. smokes a cigarette through a machine linked to its windpipe by a plastic tube to test any link between smoking and emphysema. (Photo by AP Photo)

Skeleton involves a person riding a small sled down a frozen track while lying face down. The sport is a more intense form of luge because skeleton competitors leap onto the sled and slide downhill head first. Skeleton athletes can reach up to 80 mph on straightaways, causing forces up to 5g, so the helmet is a critical component for attitude as well as safety.

A visitor passes behind the sculpture “Puma-Dentist” made with plastic, wax and original heads of a puma and a hind by Austrian artist Deborah Sengl during an exhibition at the art gallery Deschler in Berlin April 15, 2008. (Photo by Fabrizio Bensch/Reuters)

A man walks on the Cobb as storm waves break behind on December 13, 2011 in Lyme Regis, England. (Photo by Matt Cardy/Getty Images)

Three secondary schoolboys smoking an illicit cigarette in Hyde Park, London. (Photo by Evening Standard/Getty Images). May 1972

A couple covered with the US and the pride flags pay their tribute for the victims of a 12 June mass shooting in Orlando, Florida, USA, as they look at the Eiffel tower, illuminated in rainbow colours, in Paris, France, 13 June 2016. A total of 50 people including the suspect were killed and 53 were injured in a shooting attack at an LGBT club in Orlando, Florida, in the early hours of 12 June. The shooter was killed in an exchange of fire with the police after taking hostages at the club. (Photo by Yoan Valat/EPA)

A freighter trapped in ice is shown in this aerial photo near Whitefish Bay on Lake Superior northwest of Sault Ste. Marie, Ontario April 7, 2015. The biggest ice cover on the Great Lakes in decades is backing up shipments of everything from Canadian grain to U.S. iron and steel in one of North America's most important economic regions. (Photo by Kenneth Armstrong/Reuters)

Reuters photographer Bobby Yip took a series of portraits of people taking part in the “Occupy Central” protests in Hong Kong, and asked them why they had joined the demonstrations. China rules Hong Kong under a “one country, two systems” formula that accords the territory limited democracy. Tens of thousands of mostly student protesters are demanding Beijing give them full democracy, with the freedom to nominate election candidates. The unrest is the worst in Hong Kong since China resumed its rule over the former British colony in 1997. (Photo by Carlos Barria/Reuters)