Iranian city has most polluted air in world

Cities in Iran, India, Pakistan and the capital of Mongolia rank among the worst on the planet for air pollution, according to the first such global survey, released by the World Health Organisation (WHO).

The south-western Iranian city of Ahvaz had the highest measured level of airborne particles smaller than 10 micrometers.

WHO released the list yesterday to highlight the need to reduce outdoor air pollution, which is estimated to cause 1.34 million premature deaths each year. The global body said investments to lower pollution levels quickly pay off due to lower disease rates and, therefore, lower healthcare costs.

The list, which relies on country-reported data over the past several years, measures the levels of airborne particles smaller than 10 micrometers (PM10s) for almost 1,100 cities.

WHO recommends an upper limit of 20 micrograms for PM10s, which can cause serious respiratory problems in humans. They are mostly sulphur dioxide and nitrogen dioxide from power plants, auto exhausts and industry.

Ahvaz’s annual average of PM10s was 372 micrograms per cubic metre. Heavy industry and low-quality vehicle fuel are the main causes of air pollution in the desert city of 1.3 million.

The study found the Mongolian capital Ulan Bator had an annual average PM10s density of 279 micrograms per cubic metre, followed by another western Iranian city, Sanandaj, with 254 micrograms. Quetta in Pakistan and Kanpur, in India, and Botswana’s capital Gaborone, also ranked high on the list.

Mohammad Hasan, 39, of Karachi, Pakistan, said attempts to improve air quality in the port city of 18 million - such as by replacing heavily polluting buses with vehicles using compressed natural gas - are being undermined by bigger polluters who are “playing havoc with the lives of Karachi populace”.

“Industries and factories are emitting thick clouds of smoke, and no government agency is out there to check them or correct them,” he said.

WHO said the reasons for high pollution levels varied, but that often rapid industrialisation and the use of poor quality fuels for transportation and electricity generation are to blame.

In India, major metropolitan areas such as New Delhi, Mumbai and Kolkata have banned the construction of new power plants within city limits, and existing ones are being shut down or relocated.

At the other end of the list, Canadian city of Whitehorse, the capital of Yukon, with a yearly average of just three micrograms of PM10s per cubic metre.