NEW DELHI - India's state air monitoring centre made a rare admission Thursday that pollution in New Delhi was comparable with Beijing, but disputed a WHO finding that the Indian capital had the dirtiest atmosphere in the world.
A study of 1,600 cities across 91 countries released on Wednesday by the WHO showed Delhi had the world's highest annual average concentration of small airborne particles known as PM2.5 of 153.
These extremely fine particles of less than 2.5 micrometres in diameter are linked with increased rates of chronic bronchitis, lung cancer and heart disease as they penetrate deep into the lungs and can pass into the bloodstream.
Indian officials in the past have bristled at research showing the capital as worse than Beijing where thick smog has triggered public health warnings and public concern that are mostly absent in New Delhi.
"If we compare yearly averages for each year from 2011-2014 then both cities (New Delhi and Beijing) are almost comparable," Gufran Beig from India's state-run System of Air Quality Weather Forecasting and Research (SAFAR) acknowledged in an email sent to AFP.
He disputed the figure cited by the World Health Organisation (WHO) for PM2.5 in New Delhi, however, saying it should have been in the range of 110-120 micrograms per cubic metre instead of 153.
Beijing's was underestimated at 56, he said, and should have been double this according to an analysis of readings given out by the US embassy in the city.
"Delhi's air quality is better than Beijing in summer and much better in monsoon season," he added. "It is winter pollution in Delhi and sudden spikes which is quite high as compared to Beijing, triggered by meteorology." Beig maintained that the WHO figures contained in a searchable database released on Wednesday were biased and misleading.
But even with an annual average PM2.5 reading of 110-120, New Delhi would still be among the world's most polluted cities, if not the outright worst.
Rivals would be the Pakistani city of Karachi with an annual reading of 117, while the regional Indian cities of Gwalior, Patna and Raipur reported 144, 149 and 134 respectively.
By comparison, London had an annual PM2.5 reading of 16.
"The latest urban air quality database released by the World Health Organisation reconfirms that most Indian cities are becoming death traps because of very high air pollution levels," said Indian campaign group the Centre for Science and Environment.
It said that 13 of the 20 most polluted cities in the world were in India.