People avoid the heat in an air-raid shelter in Chongqing. [Photo provided to chinadaily.com.cn]

Air-raid shelters are chambers, often underground, reinforced against airstrikes, natural disasters and other emergencies.

Chongqing, located in Southwest China, is a place of undeniable strategic significance. And because of the geographical structure and climate, frequent natural disasters, such as torrential downpours, landslides and debris flows, pose daunting challenges to the city.

As a result, Chongqing has a wide distribution of air-raid shelters.

People visit a museum in an air-raid shelter in Chongqing on Sept 3, 2019. [Photo by Zhang Zhi / provided to chinadaily.com.cn]

But in a new era where people don't need to worry too much about wars, and major natural hazard prevention capabilities have been constantly improving, air-raid shelters have taken on a new life in Chongqing.

Now the city uses air-raid shelters as tunnels, gas stations, restaurants, cellars and even free places to cool down, providing convenience to local residents.

According to the People's Air Defense Office of Chongqing, the usage rate for air-raid shelters in the city has reached as high as 93 percent, with around 25 million people having stayed in the shelters to escape the heat.