Delhi's air quality plunged to 'very poor' just two days after staying in the 'poor' category, on Wednesday. The Central Pollution Control Board (CPCB) recorded the overall Air Quality Index (AQI) of the city at 328 at 4:30pm. Meanwhile, firefighting operations continued at the Bhalswa landfill site, with experts warning that the toxic fumes emanating from the fire were adding to the spiked pollution levels in the national capital.

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'.

Air quality had improved marginally on Monday, moving from 'very poor' to 'poor' category, but experts said the blaze at Bhalswa landfill site could deteriorate the air.

A Delhi Fire Service official said firefighting was still on at the garbage dump site."Due to continuous discharge of methane gas from the landfill, fire erupts randomly. Two fire tenders are currently working on containing the fire at the site," he said. The inferno has been raging at the massive dump site since October 20. However, by Tuesday evening, the flames were somewhat brought under control and parts of the landfill smouldered, DFS officials had said.

On Sunday, the AQI had oscillated between 'poor' and 'very poor' categories while on Saturday, a haze had engulfed the national capital, recording the worst air quality of this season at 324.North Delhi Mayor Adesh Gupta and NDMC Commissioner Madhup Vyas had visited the landfill site on Tuesday. The civic body had announced a slew of measures, both long-term and short-term for remediation of the site. The Supreme Court-appointed Environment Protection Control Authority (EPCA) Friday had held a meeting with officials of Punjab, Haryana and the Delhi governments to discuss the pollution situation in the national capital.

To curb pollution levels around Diwali, the Supreme Court on Tuesday only allowed the use of "green" firecrackers, but it was unclear how the rule will be enforced or whether there was such a thing as an environmentally safe firework.

UNDER CONTROL

• A Delhi Fire Service official said firefighting was still on at the garbage dump site.   
• Two fire tenders are currently working on containing the fire at the site, said fire officer   
• The inferno has been raging at the massive dump site since October 20.