This statement is not entirely true. While it may be difficult to determine which city is the most polluted overall, there are various organizations and institutions that conduct research and produce reports on air quality, water pollution, and other environmental indicators. These reports provide valuable insights into the pollution levels of cities around the world. For example, the World Health Organization (WHO) regularly publishes reports on air quality, highlighting cities with high levels of air pollution based on specific criteria and measurements. Additionally, organizations such as the United Nations Environment Programme (UNEP) and the World Bank release reports on pollution levels in different regions and cities, providing data and analysis on various pollutants. While determining the "most polluted" city can be subjective and depend on the specific pollutants and criteria considered, these reports offer valuable information on pollution levels and help raise awareness about environmental challenges in urban areas.