A man weighs a 100-day-old infant. [PHOTO BY ZHENG XIANZHANG FOR CHINA DAILY]

One of his most notable projects was on a residential neighborhood in Putuo district that used to be the city's largest shanty town. He can still remember the time he was invited into one of the homes in this area.

"It was shocking to see how a tiny 4-square-meter room could have been the home for this old couple. When I took their picture, the couple said they had been waiting for years to be relocated to a bigger, more comfortable home. They weren't sure if they would still be alive when they finally got to move," he says.

In early 1990s, the per capita living space in Shanghai was less than 4 square meters. Now the housing situation in the city has totally changed. Authority statistics show that the per capita living area was 36 sq m by the end of 2018.

Despite his age, Zheng is still very much active in the photography scene. Luo Ying, the deputy editor-in-chief of the Shanghai Culture Publishing House and former deputy editor-in-chief of the Shanghai Pictorial, is one person who can testify to this.