A separate annual world ranking elaborated by IQAir (owner of AirVisual) in partnership with Greenpeace in March showed that Hanoi was not in the world’s top 200 most polluted cities last year.

In the list of the world's most polluted city by AirVisual and Greenpeace
in 2018, Hanoi ranked 209. Photo: Nguyen Ngan

Even though Hanoi has been number 1 in the AirVisual’s ranking of major polluted cities at certain times over recent days, it does not mean that Hanoi is the world’s most polluted city, AirVisual said on its website.

The “major cities ranking” currently consists of around 90 global megalopolises, AirVisual said, adding that at a certain moment, a city can top the live ranking, as it happened with London and even San Francisco last year.

A separate annual world ranking elaborated by IQAir (owner of AirVisual) in partnership with Greenpeace in March showed that Hanoi was not in the world’s top 200 most polluted cities in 2018, AirVisual wrote.

 It stressed that for determining Hanoi air quality, AirVisual uses data from the governmental Hanoi Environmental Monitoring Portal and the US embassy to report real-time air pollution levels.

 According to AirVisual, providing a list of polluted cities will help people be aware of pollution level and take actions. 

 “That’s what happened in Beijing. When people realized how serious the air pollution was, they pushed the government to implement stronger environmental policies. As a result, Beijing pollution has dropped dramatically,” it cited.

 In the list of the world's most polluted city by AirVisual and Greenpeace in 2018, Hanoi ranked 209. The most polluted cities were in China and India. The survey was based on the average results of each month in the whole year.