New Delhi

A layer of smog lingers in Delhi's sky as the air quality in the national capital continue to remain in the 'very poor' category on Tuesday morning with an overall Air Quality Index (AQI) at 321, as per the System of Air Quality and Weather Forecasting And Research (SAFAR).

On Monday morning the overall AQI of the city stood at 326. The National Capital Region (NCR) also continued to witness bad air as Noida also registered very poor air quality with an AQI of 354 while Gurugram's AQI stood at 326 and continued to remain in the 'very poor' category.

The level of PM 2.5 and PM 10 was recorded at 147 in the 'very poor' category and 275 in the 'poor' category respectively in Delhi. AQI recorded at all major monitoring stations in the national capital also stood in the 'very poor' category. Pusa recorded AQI of 322 while Dhirpur recorded an AQI of 339.

Lodhi Road recorded 317, Delhi Airport (T3) recorded an AQI of 323 and Mathura road recorded an AQI of 338. The AQI at Delhi University stood at 336. while that at IIT Delhi stood at 293 in 'poor category.' Ayanagar also was in the 'very poor' category at 330 at 8:45 am on Tuesday.

Air Quality Index from 0 to 100 is considered as good, while from 100 to 200 it is moderate, from 200 to 300 it is poor, and from 300 to 400 it is said to be very poor and from 400 to 500 or above it is considered as severe. Following the improvement in Air Quality Index in relative terms, the Delhi government on Monday lifted various bans, imposed earlier, including the ban on the entry of trucks into the national capital.

The Delhi government also revoked directions for the closure of schools and work from home for 50 per cent of staff in government offices. The directions were issued in view of the Central government's panel Commission for Air Quality Management (CAQM) to revoke the Graded Response Action Plan (GRAP) stage 4 after the national capital's air quality turned 'severe' last week.

However, the curbs on BS III petrol vehicles and BS IV diesel vehicles will still continue in Delhi. Delhi Environment Minister Gopal Rai said the ban was imposed under Stage III of the Graded Response Action Plan (GRAP); and that it won't be lifted yet.

On Sunday, in view of the improvement in the overall air quality of the Delhi-NCR in the past few days, a Central government panel revoked the Graded Response Action Plan (GRAP) stage 4. But a ban on non-essential construction activities which come under GRAP-3 now in force would continue.