Extreme heat causes a surge in spontaneous glass shattering throughout China

Following consecutive days of high and humid temperatures, there have been incidents of glass shattering across China. A glass installer said that he has already replaced 60 glass panels in the past two months, averaging nearly one per day, China National Radio (CNR) reported.
The sweltering heat has tested the limits of glass. Recently, incidents of glass shattering due to high temperatures have been reported across the country, CNR reported.

A resident surnamed Tian from Zhengzhou, Central China's Henan Province, noticed that the inner layer of the glass in his bathroom window cracked into a spiderweb pattern on a recent morning. 

He noted that while the air conditioning in the room was set to around 27 C, the bathroom window, facing east, was exposed to direct sunlight.

“I didn’t hear any noise,” Tian said, adding that since it cracked from the inner layer, it was unlikely to have been caused by an external impact. 

“I suspect it was due to the extreme heat," he said.  

A glass installation worker said that cases of spontaneous glass breakage have surged in the past two months — he has replaced 60 glass panels, averaging one per day, according to the CNR.

According to industry insiders, glass naturally contains tiny crystalline impurities. When there is a significant temperature difference between indoor and outdoor environments, thermal expansion and contraction can occur, which can cause spontaneous breakage, experts said.

Such incidents typically peak from May to October each year, as high temperatures amplify the indoor-outdoor temperature differential, increasing the risk of glass shattering, CNR said. 

Earlier in July, due to consecutive days of high temperatures, a glass panel at a bus shelter in Changsha, Central China's Hunan Province, experienced spontaneous shattering. Fortunately, no casualties were reported, as confirmed by staff from the Changsha bus shelter management department, Xiaoxiang Morning News reported.

As many as 152 national-level meteorological observation stations across China have recorded high temperatures exceeding 40 C since the beginning of July, China Meteorological Administration (CMA) reported on Wednesday.