How Does a Gas Mask Protect Against Chemical Warfare?

In Israel, people are scrambling to get gas masks in case of a possible attack.

Hundreds of Israelis are lining up outside local distribution centers this week to collect protective gas masks following a series of reported chemical weapons attacks in Syria. If the United States does intervene in Syria, neighboring Israel fears being the target of a counterattack.

Speaking from the Department of State on Friday, Secretary of State John Kerry announced a death toll of 1,429 people from a Syrian chemical weapons attack, including at least 426 children. If Israel was caught up in this deadly chemical warfare, could gas masks provide effective protection to its people? (Realted: "Chemical Warfare, From Rome to Syria. A Time Line.")

To understand the workings behind a modern-day gas mask—an invention that dates back to World War I—National Geographic spoke with John Georgiadis, a professor of mechanical engineering at the University of Illinois, who researches filtration systems