With Delhi's air quality having improved to "very poor", a Supreme Court-appointed environment body on Thursday ordered lifting of a ban on entry of trucks and on construction activities in the city.

The Environment Pollution Control Authority (EPCA) also rolled back the four-time hike in parking fees.

EPCA member and Centre for Science and Environment (CSE) researcher Usman Naseem told IANS while the restrictions imposed since last week have been lifted, the ban on diesel generator sets would continue.

On Wednesday, the Air Quality Index (AQI) of the national capital had improved to "very poor" from "beyond severe" category.

At 11 a.m. on Thursday, Delhi's AQI was 345, which falls under the "very poor" category.

Also, the average PM2.5, or particles with diameter less than 2.5mm, in Delhi was 345 units -- 14 times the safe limit, compared to 397 units on Tuesday.

On Wednesday, officials had said the EPCA might ask officials to revoke the restrictions imposed under the "severe-plus" or "emergency" category of the Graded Response Action Plan (GRAP) and replace them with those under the "very poor" category.

The severe-plus GRAP was imposed on November 7, after a thick yellow blanket of smog covered Delhi due to the cumulative effect of stubble burning in neighbouring states and meteorological reasons.

Under the "severe-plus" category, according to rules, truck movement in Delhi is stopped, construction work is banned, odd-even scheme for vehicles is imposed and schools are shut.

However, since November 7 while all other restrictions were in place following the National Green Tribunal's (NGT) intervention, the odd-even scheme could not be implemented due to a difference in views of the green court and the Delhi government, which is the implementing agency for the vehicular restriction scheme.

The very-poor GRAP comes in force when PM2.5 levels are between 121-250 units or PM10 levels are between 351-430 units. Under very-poor, diesel generator sets are banned.