New Delhi, July 26: The civil aviation ministry has asked major airports, including those in Delhi, Mumbai and Calcutta, to furnish data on noise pollution caused by flight movements.

The move follows a recent National Green Tribunal directive asking the Centre to specify noise levels at the Delhi airport between 10pm and 7am.

The tribunal had also directed the government to inform it about steps taken to monitor noise standards near other airports. The ministry has now sought such data from these airports in two time slots - late-night hours (10pm to 7am) and peak hours of the day (9 to 11am and 6 to 9.30pm).#"We have asked all major airports to collate and provide similar data during peak operational hours. It will help us decide on measures to control noise pollution," a senior ministry official said.

While the airports in Delhi, Mumbai, Hyderabad, Bangalore and Kochi are run in public-private partnership mode, most others are managed by the Centre-owned Airports Authority of India (AAI).

Noise Pollution (Regulation and Control) Rules, 2000 - issued by the Union environment and forests ministry - put airports under "industrial zones" where the noise limits are 75 decibels during the day and 70 at night.

Other officials conceded there was no regular noise monitoring at airports. But some pilots termed the limit of 75 decibels "not practical" at the busier hubs.

"The noise level inside a narrow-bodied aircraft during take-off is more than 90 decibels. During taxiing, an aircraft's engines produce minimal thrust. The noise level in the cabin then is 65 decibels," said a member of the Air India Pilots' Association.

Aviation experts say noise levels within 300 metres of jet take-off points could exceed 100 decibels.

An AAI spokesperson confirmed having received the ministry letter seeking the noise-related information. However, he argued the aviation industry could not alone be held responsible. "Most airports are located at a considerable distance from city limits and that should reduce any impact of the high noise levels. But in recent years, there has been rampant construction around airports and people face more noise hazards."

Former director-general of civil aviation Kanu Gohain recalled that an internal panel had found noise levels near airports' peripheries above 90 decibels during late nights, when international flight traffic peaks. "But this is a problem all over the world. Some airports in Europe have banned flights at night. But in India, with a developing aviation industry, we cannot afford to do that."

Gohain offered one possible solution. "Local governments should ensure no development (construction) happens close to airports. Otherwise, residents will be exposed to (greater) noise pollution."

Aviation consultant Dhiraj Mathur acknowledged the "problem will be further aggravated as the aviation industry grows" but proposed a remedy. "What the government can do is set up another airport in Delhi and elsewhere further away from the city limits. That could (also) ease the pressure on existing airports."