World’s most polluted cities ranking reveals climate change influence on PM2.5

Swiss monitoring firm IQAair has published its latest World Air Quality Report, which ranks the world’s most polluted cities and reveals that climate change events are impacting on air pollution more than ever.

The 2019 World Air Quality Report reveals levels of fine particulate matter (PM2.5) and shows that climate change events, such as sandstorms and wildfires, elevated levels in countries and cities such as Singapore, Australia, Indonesia, Brazil, Kuala Lumpur, Bangkok, Chiang Mai, and Los Angeles, among numerous others.

Cities in Southeast Asia such as Hanoi and Jakarta have also seen sharp rises in levels due to increased industrialisation and urbanisation.

Using a weighted population average, Bangladesh is the most polluted country for PM2.5 exposure. Pakistan, Mongolia, Afghanistan and India follow behind respectively, deviating from one another by less than 10%.

Bosnia and Herzegovina is the highest-ranking country in Europe for PM2.5 pollution, featuring as the 14th most polluted country globally, with only 4μg/m3 less than China’s national PM2.5 weighted average.

Lukavac in Bosnia and Herzegovina, which has several chemicals factories, is Europe’s most polluted city, with an average PM2.5 level of 55ug/m3. 

Hanoi, Vietnam.

Chinese cities achieved a 9% average decrease in PM2.5 levels in 2019, after a 12% decrease in 2018. Still, 98% of cities exceeded WHO guidelines and 53% of cities exceed China’s less stringent national targets. In the last decade, Beijing has more than halved its annual PM2.5 levels and in 2019 Beijing dropped out of the ranking’s top 200 most polluted cities for the first time.

Sheffield is the UK city with the highest annual level of PM2.5 (12.7ug/m3), ranking 1597th. It’s followed by Portsmouth in 1682nd and Leeds in 1716th.

London is the 2045th most polluted city in the world for PM2.5.

While some achievements have been made in air quality monitoring infrastructure globally, IQAir says there are still huge gaps in access to data around the world and they have called on government’s to increase their monitoring.

Frank Hammes, IQAir CEO said: ‘While the Coronavirus is dominating international headlines, a silent killer is contributing to nearly 7 million more deaths a year: air pollution. Through compiling and visualizing data from thousands of air quality monitoring stations, the 2019 World Air Report reveals new context to the world’s leading environmental health threat.’