NEW DELHI  - The Chief Justice of India on Saturday asked the central government to come up with an emergency plan to tackle New Delhi's toxic air quality and dangerous smog conditions, calling the situation "very serious".

On Friday, India's federal pollution control board ordered states and local bodies to be in "complete readiness" for emergency measures to tackle worsening smog conditions in the capital.

"We have been forced to wear masks at home also, the situation is very serious," the top legal officer in the Supreme Court of India N. V. Ramana said while seeking clarity on the measures initiated by the government so far.

"Delhi air quality will become severe and increase in surface wind may help .. another two to three days it will increase further. Take an emergency decision," he said.

Delhi, often ranked the world's most polluted capital, faces extremely bad air in winter due to crop stubble burning, emissions from transport, coal-fired plants outside the city and other industrial emissions, as well as open garbage burning and dust.

While the smog reduced visibility, the Air Quality Index (AQI) in and around capital city hit 470 to 490 on a scale of 500, according to the federal pollution control board data on Saturday.

This level of pollution means the air will affect healthy people and seriously impact those with existing diseases.

A special bench of the Supreme Court has started hearing a plea filed by a student concerning rising levels of air pollution.

Ramana said the government should consider a two-day lockdown to protect citizens from the rising toxicity and inform the court on Monday about the emergency steps taken to improve air quality.

In a notification on Friday, the pollution control board said the government and private offices should reduce the use of private transport by 30% and advised the city's residents to limit outdoor exposure.

(Writing by Rupam Jain Editing by Swati Bhat and Lincoln Feast) ((Rupam.Jain@thomsonreuters.com; +91 7042133028;))