Soldiers use electronic sensors to search for missing firefighters under a line of fire trucks caught in massive gas explosions in Kaohsiung, Taiwan, Friday, August 1, 2014. A series of underground explosions about midnight Thursday and early Friday ripped through Taiwan's second-largest city, killing scores of people, Taiwan's National Fire Agency said Friday. (Photo by Wally Santana/AP Photo)

Some of London's telephone operators and engineers, trying out their gas masks at the anti-gas civilian training centre in Gloucester, where they were taught how to deal with gas attacks. (Photo by Harry Todd/Fox Photos/Getty Images). 13th February 1937

Women carry gas cylinders to fill them at a distribution point in Cairo January 19, 2015. Egypt is going through its worst energy crisis in decades and is seeking fresh sources of natural gas, which powers most of its homes and factories. (Photo by Mohamed Abd El Ghany/Reuters)

Three workers demonstrating the different types of gas masks used in mine rescue work. (Photo by Fox Photos/Getty Images). December 1925

A large molded bust of Edward Snowden is pictured in Fort Greene Park at the Brooklyn borough of New York in this April 6, 2015 picture provided by ANIMALNewYork. A group of anonymous artists erected the 4-foot-tall bronze statue of Snowden, the former U.S. spy agency contractor famous for leaking classified information, in a New York City park overnight, officials said on Monday. (Photo by Aymann Ismail/Reuters/ANIMALNewYork)

The Photo London Master of Photography award is given annually to a leading contemporary photographer. A special exhibition shows new and rarely seen images from Burtynsky’s portfolio. Here: Morenci Mine #2, Clifton, Arizona, USA, 2012. (Photo by Edward Burtynsky/Metivier Gallery, Toronto/Flowers Gallery, London)

“US Airways Flight 1549 was US Airways' scheduled domestic commercial passenger flight from LaGuardia Airport in New York City to Charlotte/Douglas International Airport, Charlotte, North Carolina. On January 15, 2009, the aircraft flying this route, an Airbus A320-214, was successfully ditched in the Hudson River adjacent to midtown Manhattan six minutes after takeoff from LaGuardia Airport after being disabled by striking a flock of Canada Geese during its initial climb out. The incident became known as the «Miracle On The Hudson»”. – Wikipedia

Photo: The Airbus jet that pilot Chesley “Sully” Sullenberger landed on the Hudson River is pulled along Yorkmont Road as it makes its way to the Carolinas Aviation Museum June 10, 2011 in Charlotte, North Carolina. An official unveiling of the plane, which will be on display at the Carolinas Avaiation Museum, will take place on Saturday, June 11. (Photo by Davis Turner/Getty Images)