City’s subway safe from gas, nuclear attack (2)

"The station has three hours of breathable air after the gates are closed, isolating the station from the outside world," said Hu, although she did not say how many people this oxygen supply could sustain.

The steel doors are installed in the tunnels and can separate each station.

"Although each gate weighs around 7 tons, it takes just three minutes for two adults to open or close it manually," she said.

"This new technical gate was introduced into subway construction projects since Subway Line 5 in 2007," said Hu, noting that compared to the previous gates, the new ones are easier to manipulate and maintain.

Another colleague of Hu, surnamed Liang, told the Global Times that each station does have an air filtration system in case of gas attack, and it will also keep air flowing into the station.

"People can actually shelter in the subway for more than three hours because of this system," said Liang.