Vietnam's capital didn't fare well in a new global air quality study.
The 2018 World Air Quality Report, compiled by IQAir, includes data on 3,000 cities and how they fared compared to the World Health Organization's (WHO) guidelines for fine particulate matter or PM2.5.
Within Southeast Asia, Hanoi had the second-worst average PM2.5 reading in 2018, according to readings from IQAir's AirVisual app. The city's average was 40.8, behind Jakarta's 45.3 and ahead of Samut Sakhon, Thailand, which clocked an average of 39.8.
Saigon, meanwhile, ranked 15th in the region, with an average 2018 reading of 26.9, while Vietnam on a whole had the 17th-worst average PM2.5 concentration in the world.
Bangladesh, Pakistan and India have the worst air quality, according to the report, with average figures of 97.1, 74.3 and 72.5, respectively.
Globally, cities performed poorly against WHO standards, IQAir found: 64% of the surveyed urban areas exceeded the organization's annual guidelines, including 100% of cities measured in Africa and the Middle East; 99% of cities in South Asia and 95% of cities in Southeast Asia.
Hanoi's poor air quality is often blamed on the city's dense traffic, along with emissions from construction projects and industrial facilities.
