The study looked at pollution in runoff water in different areas of Tianjin after rain. They found that pollutant levels were highest at the start of rainfall, then stabilized. The water quality was below standard, with many results exceeding sewage discharge limits. Tianjin's pollution levels were similar to Guangzhou, higher than Beijing and Shanghai, and much higher than the US and France. Industrial areas had the worst pollution, followed by commercial, residential, and education areas. Pollution control is crucial for improving runoff water quality in Tianjin.