Haryana, Punjab, Rajasthan and Uttar Pradesh will have to respond to the NGT by October 19.
The National Green Tribunal today warned of halting state transport in four northern states that surround the capital if they did not introduce CNG, saying most particulate matters in the air inhaled by Delhi residents emanated from there.
"What have you done with regard to introduction of CNG stations in your areas? What are you doing about this? We had asked you to submit your response on the issue. What have you done on this? I am being told that over 50 per cent of pollution in Delhi is caused by fine particulate matter which originates from neighbouring states. The air quality in Delhi is getting worse. You should take every measure to introduce CNG stations in your states. If you don't introduce CNG in you state, we will stop your state transport," a bench headed by NGT Chairperson Justice Swatanter Kumar said.
The observations came during the hearing of a case filed by Vardhaman Kaushik on the deteriorating air quality in the national capital.
The tribunal directed senior officials from states of Haryana, Punjab, Rajasthan and Uttar Pradesh, besides officers of Petroleum and Natural Gas Regulatory Board, to appear before it on October 19, the next date of hearing.
The NGT in September had asked Uttar Pradesh and Haryana government to mull over the possibility of installing CNG stations in NCR while refusing to grant permission to over 10- year old diesel vehicles to ply in these areas.
On July 18, the green panel had directed authorities in Delhi-NCR to cancel the registration of all diesel-powered vehicles which are more than 10 years old.
After de-registration, the authorities will issue public notice in this regard and supply the list of such vehicles to the traffic police to take appropriate steps in consonance with directions of tribunal, it had said.