Grap-4 enforced after air quality sees dramatic fall

A ban on all construction activities, curbs on older private vehicles, restrictions on trucks except those carrying essentials, and mandatory hybrid classes even for higher grades came into effect in Delhi-NCR on Saturday under Stage 4 of the Graded Response Action Plan (Grap) after air quality plunged into the "severe" category following a drop in wind speeds.

- Snehil Sinha and Aheli Das

Unlike the previous "severe" spell — a 24-hour average air quality index (AQI) reading above 400—the announcement of mitigative measures came with a sense of urgency. On Saturday, the AQI touched 401 in Delhi at 10am, barely breaching the "severe" mark, but the commission announced curbs under stage 3 before 11am. This was upgraded to stage 4 in the evening after the Central Pollution Control Board (CPCB) released its daily bulletin at 4pm, recording an average AQI for Delhi at 431.

To be sure, when the air turned severe from November 9, Grap 3 was invoked by the Commission for Air Quality Management (CAQM) only two days later. The AQI remained 400+ till November 13, but Grap 4 was not imposed, effectively making this the first time this season the curbs under this stage have been implemented.

The commission revoked stage 3 restrictions on November 26 at an AQI of 327, which was still firmly in the "very poor" category. This allowed construction activities to be carried out along with the plying of older diesel vehicles on roads on what was the 21st consecutive hazardous air day in the Capital.

The Delhi government issued orders to all schools to conduct classes for grades up to 9, along with 11, in hybrid mode - both physical and virtual (wherever possible) with immediate effect till further orders. It also issued an order under section 5 of the Environment (Protection) Act, 1986, to all government and private offices operating within the city to allow 50% staff to work from home. Delhi-registered heavy diesel vehicles that are BS-IV and below have also been restricted under stage 4.