While a veil of smog has been choking Delhi this week, the national pollution watchdog's data reveals Chhattisgarh's capital Raipur, Gwalior in Madhya Pradesh and Uttarakhand's Kashipur are breathing in far more polluted air than Delhi.
The air pollution numbers from 252 Indian cities released by the CPCB bring to light the darker side of India's growth story, say experts.
The rise in particulate air pollution levels - that can cause respiratory and heart ailments - in smaller cities has been much more than the metropolises, traditionally considered the worst offenders. In fact, eight of the top 10 most polluted cities are developing ones.
None of these new cities were on India's hazardous air pollution logs five years ago. India's industrial towns and metros like Delhi, Ludhiana, Indore and Kanpur topped the dirty air chart then.
But while media glare over these cities resulted in some corrective measures leading to a slowdown in the growth of pollutants, nothing like that happened in the tier-2 and tier-3 cities.
As a result, Delhi slipped to the fifth position in particulate matter pollution levels from the top rank it held for many years till 2009. Ghaziazbad, which was second on the list in 2010, slipped to ninth in 2011.
"All the attention of the policymakers and the NGOs was on the big cities," said Anumita Roy Chowdhury of the non-profit Centre for Science and Environment (CSE). "In this, we forgot about the environmental hazard brewing elsewhere."
The CPCB data also boggled policymakers as only one Indian city, Mahabalipuram, had lower than standard pollution levels in 2011 as compared to more than one-fourth of the cities monitored in 2008.
In about 60% of the cities, the annual average of the air pollution levels was high or critical. This means that in certain seasons, especially winter, the levels were alarmingly high.
Delhi and nearby areas have seen particulate matter pollution levels touching 800 micrograms per cubic metre of air as winter sets in, where the annual average in 2011 was 262.
