Over the course of the last 4 decades, the population of Kathmandu (Nepal) has exploded: from few hundred thousand people to more than 3 million people.
This ultrafast, unregulated, urbanization process has caused numerous major problems, the most dramatic being a sharp increase in air pollution.
In the 2018 global Environmental Performance Index (EPI), Nepal ranked last in terms of air quality among the 180 countries listed.