Delhi air turns very poor as Diwali firecracker limits begin

Delhi's air quality index stood at 377 on Wednesday morning, in the "very poor" band, as authorities brought a second stage of emergency curbs into force and a Supreme Court order set narrow hours for firecrackers over the Diwali weekend.

India's pollution watchdog classes readings from 301 to 400 as very poor and anything above 400 as severe. The index tracks eight pollutants, among them PM2.5, particles small enough to lodge deep in the lungs.

Stage II of the Graded Response Action Plan, which tightens as pollution rises, brings more intensive road cleaning, higher parking charges to discourage private cars and extra public transport. Delhi Metro added 20 weekday trips, and government offices have been told to stagger their hours to spread out traffic. Officials said forecasts pointed to very poor air for several days.

On Monday the Supreme Court allowed the manufacture, sale and use of certified green firecrackers in Delhi and surrounding areas, but only between 06:00 and 07:00 and between 20:00 and 22:00 local time on 7 and 8 November. It barred fireworks within 300 metres of hospitals, care homes and schools, and ordered police to patrol sales areas, check QR codes at random and seize illegal stock. Green crackers use modified chemical formulations meant to emit less, and each must carry a code identifying its maker and certification. The court noted that ordinary firecrackers had been sold as green ones even when a full ban was in force.

Delhi has restricted firecrackers in various forms over the years, and enforcement has remained difficult. Last year the city woke to a toxic haze the morning after Diwali despite a court directive to use less-polluting crackers.

According to the BBC, this year's sharp rise followed an unusually clean October, Delhi's lowest average AQI for the month in eight years. Experts cited falling temperatures, weak winds and more crop-residue burning in Punjab and Haryana. A storm had earlier cleared the air with rain and stronger winds; as the weather settled, north-westerly winds carried smoke from burning fields towards the capital.

The problem is not confined to the capital. Mumbai recorded an AQI of 322, also very poor, on 24 October, which the BBC attributed to low wind speeds, construction dust, rubbish burning, firecracker emissions and pollution drifting in from neighbouring regions. By Wednesday the coastal city had improved to 89, classed satisfactory, and Navi Mumbai stood at 118, moderate.