{4|Several} out of five city dwellers lives with {alarmingly|precariously} bad air
India has four of the 10 cities in the world with the worst recorded air pollution, the World Health Organisation said yesterday - but only because it's among the countries to actually measure the problem.
Common causes of air pollution include too many cars, especially diesel-fuelled vehicles, the heating and cooling of big buildings, waste management, agriculture and the use of coal or diesel generators for power.
On average, pollution levels worsened by 8pc between 2008 and 2013, although most cities in rich countries improved the state of their air over the same period. The WHO data, a survey of 3,000 urban areas, shows only 2pc of cities in poorer countries have air quality that meets WHO standards, while 44pc of richer cities do.
No European cities feature among the very worst polluted this year, but about half the cities in wealthy countries, primarily in Europe and the Americas, had excessive pollution. Air quality in nearly all 300 cities in poor and middle-income countries looked at was below World Health Organisation standards.
While worst-ranked India faces a "huge challenge", many countries are so bad that they have no monitoring system and cannot be included in its ranking, WHO experts said.
Globally four out of five urban dwellers lives with dangerously high pollution levels. That is driving up the risk of stroke, heart disease and lung cancer in some of the most-vulnerable populations in many of the world's poorest cities, the report said.
Sulphates, nitrates, black carbon and other air pollutants are among the greatest environmental health risks, causing more than three million premature deaths worldwide a year. The young, the old and the poor are most vulnerable.
The dirtiest air was recorded at Zabol in Iran, which suffers from months of dust storms in the summer, and which clocked up 217 on a standardised rating called a PM2.5 measure.
The next worst pair were the Indian cities of Gwalior and Allahabad - followed by Riyadh and Al Jubail in Saudi Arabia, then two more Indian cities, Patna and Raipur.
India's capital, New Delhi, was the survey's 11th worst city, measured by the amount of particulate matter under 2.5 micrograms found in every cubic metre of air. Delhi had an annual average PM2.5 measurement of 122. Tiny particulate matter can cause lung cancer, strokes and heart disease over the long term, as well as trigger symptoms such as heart attacks that kill more rapidly.
The WHO says more than seven million premature deaths occur every year due to air pollution, three million of them due to outdoor air quality.
New Delhi was ranked worst in 2014 with a PM2.5 reading of 153. It has since tried to tackle its toxic air by limiting the use of private cars on the road for short periods.
Maria Neira, head of public health, environmental and social determinants of health at the WHO, praised India for developing a national plan to deal with the problem when others have been unable to.
"Probably some of the worst cities that are the most polluted ones in the world are not included in our list, just because they are so bad that they do not even have a good system of monitoring of air quality, so it's unfair to compare or give a rank," she said. (Reuters)
