Delhi’s air quality deteriorated ahead of Diwali, with the Air Quality Index reaching 377 on Wednesday morning. India’s pollution watchdog classifies readings from 301 to 400 as “very poor”; levels above 400 are considered “severe.”
Authorities have invoked Stage II of the Graded Response Action Plan, bringing in measures to curb dust, vehicle emissions and other sources of pollution. Prolonged exposure to air in the “very poor” category can cause respiratory problems and worsen existing illnesses, with children and older people particularly vulnerable.
The worsening follows an unusually clean October, when Delhi recorded its lowest average AQI for that month in eight years. Falling temperatures, slow winds and increased crop-residue burning in neighbouring Punjab and Haryana have been linked to the recent rise. Smoke from burning fields has been carried towards the capital by returning north-westerly winds.
Diwali celebrations, which include fireworks, could add to pollution by releasing fine particles and harmful gases. On Monday, India’s Supreme Court allowed certified green firecrackers to be manufactured, sold and used in Delhi and neighbouring areas for a limited period. They may be set off only between 06:00 and 07:00 and between 20:00 and 22:00 on 7 and 8 November.
The court also prohibited fireworks within 300 metres of hospitals, care homes, schools and other designated silence zones. Green firecrackers use modified chemical formulations intended to produce fewer emissions than conventional fireworks and must carry QR codes for checking their manufacturer and certification. Police have been directed to patrol designated sales areas, conduct random QR-code checks and seize illegal products.
Enforcement has been difficult in previous years. The Supreme Court noted that conventional firecrackers had continued to be sold as green alternatives even when a complete ban was in place. Last year, Delhi was covered by toxic haze the morning after Diwali despite a court directive to use less-polluting firecrackers.
The seasonal pollution crisis has several contributing factors, including vehicle exhaust, industrial emissions, low temperatures, slow winds and crop-stubble burning in neighbouring states. During particularly severe episodes, authorities have also used measures such as hybrid schooling, work-from-home arrangements and restrictions on some vehicles.
Sources: BBC News World.