Why were reforms called for in regards to tenements?

Reformers wanted to change the tenements after learning about the poor living conditions for immigrants. This was especially caused by the book How the Other Half Lives by Jacob Riis. Riis exposes the small,cramped, and dirty conditions of these tenements and uses pictures to portray these images to the American people. Many citizens are disgusted to see how these people are forced to live and call for change.