BERLIN — Chancellor Angela Merkel of Germany has been hailed as the “climate chancellor” for her efforts to help the country shift toward renewable energy. But she has faced criticism from consumers angered by her refusal to come down harder on German automakers over a widening diesel emissions scandal.

Now, with elections scheduled for Sept. 24, Ms. Merkel is trying to address the issue. On Monday, she met with the mayors of 30 German cities plagued by poor air quality, pledging to double the amount of money earmarked for helping local governments fight air pollution.