Air quality in the national capital deteriorated Friday, gradually inching towards the 'severe' category, as parts of the massive Bhalswa landfill site continued to smoulder.

The Central Pollution Control Board (CPCB) recorded the overall Air Quality Index of Delhi at 358 this morning, which falls in the 'very poor' category.

An AQI between 0 and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", and 401 and 500 "severe".

The Centre-run System of Air Quality Forecasting and Research also reported an AQI in the 'very poor' category.

On Thursday, the capital city recorded an AQI at 331.

Faridabad, Noida, Greater Noida, Ghaziabad and Gurgaon had also recorded air quality in the 'very poor' category Thursday, according to CPCB data.

The air quality in the capital had shown signs of improvement Monday as it moved from 'very poor' to 'poor' category. However, it dipped to 'very poor' again Wednesday even as firefighting continued at Bhalswa landfill site in north-west Delhi.

A Delhi Fire Service official said Friday that a fire tender was stationed at the landfill site as parts of the dump site was still smouldering.

Fire had raged at the landfill site on October 20. However, by Tuesday evening, the flames were somewhat brought under control, DFS officials had said.

Meanwhile, the South Delhi Municipal Corporation Thursday decided to intensify work on stopping incidents of waste and leaves burning by conducting night patrolling in all four zones of SDMC.

(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)