Calcutta: Environment experts in the city have criticised the draft "national clean air plan" (NCAP), recently introduced by the environment ministry to combat air pollution as being "too Delhi-centric".

The draft was on the Union ministry's site till May 17 and comments were invited from the general public.

The rate of increase in the level of PM2.5, the most toxic air pollutant, has been the highest in Calcutta among all metros, according to WHO.

"While Delhi and its surroundings have about 30 automatic air pollution monitoring stations; Calcutta has only two," said Naba Dutta of Sabuj Mancha. "The plan observed two to three stations would be adequate for cities in the Gangetic plains."

But S.M. Ghosh of Kolkata Clean Air said Calcutta metropolitan area alone needs at least 40 monitoring devices.

Sabuj Mancha has written to environment minister Harsh Vardhan demanding that the plan should not be formalised.