The Commission for Air Quality Management on Monday said curbs under Stage III of the Graded Response Action Plan, including a ban on non-essential construction and demolition work, will remain in force in Delhi-NCR as pollution levels are showing an upward trend.

A layer of smog blanketed Delhi and blurred landmarks from view as low temperatures and calm winds trapped pollutants close to the ground.

The 24-hour average Air Quality Index (AQI) stood at 357 on Monday, worsening from 259 on Sunday.

Moderate to dense fog may push the air quality close to the 'severe' category on Tuesday morning. An AQI between 201 and 300 is considered 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.

At a review meeting, the sub-committee on the Graded Response Action Plan (GRAP) noted that air pollution in Delhi is "showing an increasing trend due to low wind speeds and unfavourable weather/meteorological conditions".

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"Considering this, the sub-committee has decided that the ongoing actions implemented under Stage III of GRAP shall continue for the present," it said.

In view of a spike in air pollution, the Commission of Air Quality Management (CAQM) had on Friday directed implementation of the curbs under Stage III of GRAP in Delhi-NCR.

About GRAP

GRAP is a set of anti-air pollution measures followed in the capital and its vicinity according to the severity of the situation.

It classifies the air quality in Delhi-NCR under four different stages: Stage I - 'Poor' (AQI 201-300); Stage II - 'Very Poor' (AQI 301-400); Stage III - 'Severe' (AQI 401-450); and Stage IV - 'Severe Plus' (AQI>450).

If the AQI is projected to reach the 'severe' category, restrictive actions under Stage III are to be invoked at least three days in advance. These include a ban on non-essential construction and demolition, closure of stone crushers and mining activities in the region.

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The next stage - "Severe Plus" category or Stage IV - includes steps like a ban on the entry of trucks into Delhi, allowing 50 per cent of staff to work from home in public, municipal and private offices, closure of educational institutions and the plying of vehicles on an odd-even basis, etc.