The Supreme Court on Monday refused to relax the implementation of emergency measures under Stage 4 of the Graded Response Action Plan, or GRAP, until Delhi’s air quality index shows a “downward trend”, Live Law reported.

A downward trend, or declining index value, would indicate consistent, daily improvements in the capital’s air quality.

GRAP is a set of incremental anti-pollution measures that are triggered to prevent the worsening of air quality once it reaches a certain threshold in the National Capital Region. Stage 4 of GRAP includes a ban on trucks entering the region and halting construction activities for public and private projects.

A bench of Justices Abhay S Oka and Augustine George Masih on Monday said that it would take a call on relaxing the restrictions, which are enforced by the Commission for Air Quality Management in the National Capital Region, on Thursday after taking into account any improvement or deterioration in capital’s air quality.

The bench has been dealing with a matter related to air pollution caused by stubble burning, firecrackers, vehicular emissions, garbage burning and industrial pollution in Delhi and surrounding areas.

On November 17, amid worsening pollution, the air quality panel ordered the implementation of Stage 4 of GRAP across the National Capital Region.

On Monday, the average air quality index, or AQI, in Delhi stood at 277 – indicating “Poor” air quality – at 7.30 pm, according to data from the Central Pollution Control Board. The figure fell below the the 300-mark a day earlier after more than a month of being in the “Very Poor” category.

An index value between 0 and 50 indicates “Good” air quality, between 51 and 100 indicates “Satisfactory” air quality and between 101 and 200 indicates “Moderate” air quality.

As the index value increases, air quality deteriorates. A value of 201 and 300 means “Poor” air quality while between 301 and 400 indicates “Very Poor” air. Prolonged exposure to such air quality can lead to serious respiratory illnesses in otherwise healthy people.

Between 401 and 450 indicates “Severe” air pollution while anything above the 450 threshold is termed “Severe Plus”.

At the hearing on Monday, Additional Solicitor-General Aishwarya Bhati, representing the Commission for Air Quality Management, sought relaxations in the enforcement of GRAP as its prescriptions were “disruptive”.

“The AQI is not stable,” Oka said in response. “It has increased. We will look at your suggestions but today we will not permit relaxation.”

“We will apply our mind to these suggestions but we want to ensure that there is a downward trend before we permit relaxations,” the court said. “Ultimately, someday we will have to leave it to you [air quality panel], but at least we must be satisfied that there is some consistent downward trend.”

The court also took note of the failure of the states in the National Capital Region to comply with its earlier direction to compensate labourers whose livelihoods were affected by the ban on construction activities under GRAP, The Indian Express reported.

“We want proof of payment,” the bench said, according to Bar and Bench. “We find that none of the NCR [National Capital Region] states have complied with our direction to pay compensation to construction workers. Not even proof of a penny being paid has been shown.”

It directed the chief secretaries of Delhi, Haryana, Uttar Pradesh and Rajasthan to appear before it virtually on the next date of hearing and explain their positions in the matter.

The bench said that “unless substantial compliance with actual payment of amounts to the construction workers is reported, we will have to consider initiating action against the contempt of courts act against erring officers”.

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