Based on your description of the painting, it most likely illustrates the environmental impact of steel mills. The presence of steamboats on rivers alongside steel mills that produce smoke and pollution captures the consequences of industrial activity during the Industrial Revolution. This reflects how industrialization, while advancing technology and transportation, also led to significant environmental degradation.
What the painting shows us is the integration of heavy industry and transportation, highlighting the reliance on steamboats for commerce and the contrasting pollution produced by nearby steel mills. However, what is not shown here are the broader social implications, such as the working conditions in these mills, the health impacts on local populations, and the changes in labor dynamics that were also critical aspects of the Industrial Revolution.