The world’s most polluted cities

Data from the World Health Organisation (WHO) has revealed which country in the world has the most polluted air – and which city in South Africa carries the country’s top dishonour.

The WHO tracked data from over 1,600 cities between 2008 and 2013.

The annual mean concentration of particulate matter with an aerodynamic diameter of 10 μm or less in the countries’ urban population was estimated on the basis of measurements in cities within the countries.

According to the WHO, exposure to particulate matter increases the risk of acute lower respiratory infection in children under 5 years of age, chronic obstructive pulmonary disease, ischaemic heart disease, stroke, and lung cancer.

In new estimates, the WHO reported that, in 2012, around 7 million people died – one in eight of total global deaths – as a result of air pollution exposure.

Ranked by milligrams of pollutant per cubic metre, Pakistan is the the most polluted country in the world where data is tracked, with 282mg of particles (PM10) per cubic metre.

Afghanistan (268mg/m3), Bahrain (254mg/m3), and Senegal (179mg/m3) take up the other top spots.

China, which is widely regarded as one of the most polluted countries, ranks further down the list than would be expected – 15th – with ‘only’ 90mg of particles per cubic metre.

South Africa is ranked 30th across all the countries, with an exposure rate of 56mg per cubic metre.

Iceland (9mg/m3), Canada (11mg/m3), and Finland (12mg/m3) have the cleanest air in the world, according to the WHO’s data.

Top 10 most polluted countries in the world

On a city scale, the WHO tracks matter with a diameter of 2.5um (PM2.5), which is frequently cited as the most detrimental to health and well-being, as it can travel deep into lungs and cause a variety of ailments.

Globally, Delhi in India is the most air-polluted city in the world with 153ug (micrograms) per cubic metre. Indian cities account for 6 of the top 10 most polluted cities by this measure.

Top 10 most polluted cities (PM2.5)

Conversely, Powell River in Canada can be regarded as the world’s cleanest area, with air pollution of only 2ug per cubic metre.

Canadian cities, along with some notable regions in the USA (Lake Havasu, Bellingham, Durango), New Zealand, Australia (Melbourne), and Sweden have an air pollution density of 5ug per m3, or less.

South African cities

Unsurprisingly, as the most populous city in South Africa, Johannesburg is the most polluted.

With a particle density of 51ug per cubic metre, the city ranks top in South Africa, and 99th in the world.

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