From India Ink at the NYT:

But in New Delhi on Thursday, air pollution levels far exceeded those in Beijing, only without any government acknowledgement or action. It is not the first time pollution in India’s capital has outpaced that in China.

The level of tiny particulates known as PM 2.5, which lodge deep in the lungs and can enter the bloodstream, was over 400 micrograms per cubic meter in various neighborhoods in and around Delhi Thursday, according to a real-time air quality monitor. That compared to Beijing’s most-recent air quality reading of 172 micrograms per cubic meter. (The “Air Quality online” link to the left of the Delhi website gives you real-time monitoring of Delhi’s pollution levels.)

At the University of Delhi’s northern campus at 12:30 p.m., the reading for PM 2.5 was 402 micrograms per cubic meter; in the eastern suburb of Noida it was 411; at the Indira Gandhi International airport it was 421.
Having spent winters in Delhi, I can attest to the intensity of the air pollution. Part of the problem, like in other large cities, relates to winter meteorology; another significant component is the location of industry and power production in close proximity to urban population centers.

I’m working on culling the data from the Indian Ministry of Earth Sciences air pollution monitors; check back soon.