Arthur Smith, who has died in Knowlton at the age of 90, was a Canadian scientist who worked with the International Atomic Energy Agency (IAEA) and shared in the recognition when the UN agency was awarded the Nobel Peace Prize in 2005.

Mr. Smith was a pacifist all his life, and his later work was devoted to the peaceful uses of nuclear power. During the Chernobyl disaster in 1986 when the Soviet Union covered up the explosion of the nuclear reactor, Mr. Smith discovered radiation in his own backyard in Vienna, Austria, where he was working.

Arthur Smith grew up in Ottawa, where as a student he was an assistant to the famous photographer, Malak Karsh. At McGill University he met and married Mariette Hayeur. “My mother was a francophone. She didn’t speak English until she was 19,” said her daughter Michelle Smith. “At home, my mother spoke French to us, my father spoke English.”

In retirement, the couple bought a 71-acre farm in Fulford. He worked with Renaissance Lac Brome. As a scientist, he was convinced that the cause of the annual algae bloom in the lake was septic tanks by the shore leeching phosphorous into the lake.

Arthur Young Smith was born on September 4, 1929, in Detroit, Michigan, where his Canadian father lived. He died on August 23, 2020. His wife died in 1998.

His children Robin and Michelle survive him, as do three grandchildren.