Delhi’s air turns ‘very poor’; Grap 2 enforced

NEW DELHI: Layers of smog and the acrid sting of pollution cloaked the Capital on Diwali eve, prompting the Commission for Air Quality Management (CAQM) to invoke stage 2 measures under the Graded Response Action Plan (Grap), as residents braced for yet another festive day marred by toxic air before the celebrations kicked off.

- Jasjeev Gandhiok

The 24-hour average Air Quality Index dipped to 296 (poor) at 4pm, from Saturday's 268 at the same time, according to data from the Central Pollution Control Board. However, the number at 4pm progressively began to surge upwards after dusk, breaching the “very poor” threshold to touch 300 by 6pm. It settled at 310 at 11pm. Weather experts warned that the situation is unlikely to abate till the end of the week. This is the first time since February 2 that Delhi's AQI turned “very poor”. It was 326 on that day.

The Air Quality Early Warning System (AQEWS) for Delhi has predicted the number will touch the dirtier side of the "very poor" zone on Diwali.

With an increase in firecracker emissions on the day of, AQI levels will be pushed into the "severe" zone on Tuesday, it said. Experts said the impact of the additional emissions is set to hang in the air this week as surface winds will stay calm till Friday. Seasonal transport winds, predominantly northwesterlies, also aid in bringing stubble fire smoke from neighbouring Punjab and Haryana.

Twelve preventive measures are undertaken to mitigate air pollution under Grap stage 2: Among them, stricter enforcement on restrictions related to diesel generator sets; restricting interstate buses (other than EVS/CNG/BS-VI diesel) from entering Delhi and enhancement of parking fees to discourage use of private transport are key.

The harmful conditions are usually down to a toxic cocktail of stagnant surface winds, low temperatures, emissions from tailpipes and widespread bursting of firecrackers and the uptick in stubble fires in the farmlands of Punjab. However, data from the Centre's Decision Support System (DSS) showed that Sunday's deterioration was largely due to cross-boundary pollution from NCR towns factoring in 67.89% of Delhi's total PM2.5 load. The rest, 32.11%, was due to local sources.