What societal issues were expressed by Sheba Chachi, Ravi Agarwal, and Atul Bhalla through their photography in the period after 1990?

Pollution of rivers and urban congestion

Answer: Pollution of rivers and urban congestion
These artists often expressed their concern about ecology, including issues like pollution of rivers and urban congestion.

Photography could also be used to document changes in society as artists saw them. Sheba Chachi, Ravi Agarwal and Atul Bhalla, among others, photographed those, who lived on the margins of our society, whom we do not notice much in our day-to-day life — women ascetics, queer people, and so on. Often, they would express their concern about ecology like pollution of rivers and urban congestion. Photography and video have inspired many contemporary artists.