"You all (states) tell us what steps you will take at what level of pollution. What are your normal steps to check pollution," the bench said.
During the proceeding, Delhi government filed an action plan to tackle the problems recommending ban on construction activities and entry of trucks and implementation of odd-even plan, among other steps.
The NGT had on December 4 lashed out at the Delhi government for not filing a comprehensive action plan on ways to deal with severe air pollution in the city and slammed authorities for holding the India-Sri Lanka cricket match despite bad air quality.
On November 28, it had asked the AAP government and four neighbouring states of Punjab, Haryana, Uttar Pradesh and Rajasthan to submit an action plan on tackling pollution.
It had earlier directed the Central Pollution Control Board, Delhi Pollution Control Committee and every state pollution control boards to file ambient air quality analysis before the tribunal on a monthly basis and also put up on their websites to enable the concerned authority to take effective steps to control air pollution.