Pollution rankings can vary depending on the type of pollution being measured, such as air, water, or soil pollution. For air pollution, one common metric is the level of PM2.5 (particulate matter smaller than 2.5 micrometers) in the air.

As of recent reports, some countries with high levels of air pollution include:

1. India: Major cities like Delhi often report very high levels of PM2.5.
2. China: Large urban areas, such as Beijing, have faced significant air pollution challenges.
3. Bangladesh: Dhaka and other cities experience severe air pollution.
4. Pakistan: Cities like Karachi and Lahore report high pollution levels.
5. Nepal: Kathmandu has faced high levels of air pollution.

Water pollution rankings can be assessed through factors like contamination of water bodies, availability of clean drinking water, and pollution levels in rivers and lakes.

For specific, updated rankings, you might want to consult reports from environmental organizations such as the World Health Organization (WHO), the World Bank, or the Environmental Performance Index (EPI), which regularly publish detailed analyses on environmental pollution and related issues.