Billions of people in cities around the world are exposed to dangerous air, but pollution levels vary widely – and the fast-growing cities of Asia and Africa are the worst affected.
We’ve broken down data from the World Health Organization on ultra-fine particles of less than 2.5 microns (PM2.5s) region by region. Paris’s air may have almost twice as many PM2.5s as WHO recommended levels (18 micrograms per cubic metre compared with 10µg/m³) – but Delhi’s air contains 122µg/m³, while Zabol, Iran, is the worst at 217µg/m³.
Tetovo in Macedonia – a city of 50,000 near the Kosovo border – has the worst PM2.5 air pollution in Europe, according to the WHO data.
Once Turkey is included, that country claims eight of the top 10 spots in the most polluted European cities.
The most polluted cities in the US and Canada are dominated by California. The highest ranking goes to the small cities of Visalia and Porterville, midway between San Francisco and Los Angeles, in an agricultural valley known as “America’s salad bowl”.
Elsewhere in North and South America, Coyhaique in Chile ranks worst. Wood burning and lack of rainfall are thought to be contributing factors.
Bamenda in Cameroon tops the pollution list for Africa.
Every city in New Zealand and Australia at least matches the WHO’s recommended 10µg/m³.
Selected cities
Paris banned cars from the centre in response a spike in bad air at the end of last year, while London last month issued its first warning of “very high” pollution. In a global context, PM2.5 pollution levels in major European cities appear relatively low.
Lima in Peru comes out worst for major cities in North and South America. Los Angeles just breaks WHO guidelines.
Kampala in Uganda ranks worst for major African cities.
The Indian capital Delhi remains the worst major Asian city for PM2.5 air pollution.
Riyadh in Saudi Arabia ranks the worst in the Middle East.
PM10 pollution
Ranking the 20 worst cities in the world for pollution of PM10s – which are larger but considered slightly less dangerous than PM2.5s – puts Onitsha in Nigeria in clear last place. The fast-growing port and transit city recorded PM10 levels almost 30 times the WHO recommended level of 20µg/m³.
The table above headed “10 worst in the United States and Canada” was amended on 7 March 2017. An earlier version included Courtenay, Canada, with a figure of 17 micrograms per cubic metre. That was the figure recorded in the World Health Organization database for the PM2.5 annual mean in Courtenay in 2013, but the WHO now says it was incorrect and that the correct 2013 figure is 11 micrograms per cubic metre.
Guardian Cities is dedicating a week to exploring one of the worst preventable causes of death around the world: air pollution. Explore our coverage here and follow Guardian Cities on Twitter and Facebook to join the discussion
Comments (…)
Sign in or create your Guardian account to join the discussion