Air quality worsens in Delhi and parts of northern India ahead of Diwali weekend

Authorities have stepped up pollution-control measures, while India's Supreme Court has allowed certified green firecrackers to be used during restricted hours on 7 and 8 November.

Delhi is stepping up efforts to contain rising air pollution as deteriorating weather conditions contribute to a seasonal decline in air quality, with authorities introducing additional restrictions ahead of Diwali.

According to BBC, the Indian capital's air quality index (AQI) has moved above 300, placing it in the 'very poor' category. At the time of writing on 6 November, the city's AQI stood at 673.

The AQI tracks concentrations of eight major air pollutants, including PM2.5. These fine particles, measuring approximately 30 times smaller than the width of a human hair, can travel deep into the lungs when inhaled.

Exposure to polluted air can contribute to respiratory problems and aggravate existing health conditions. Children and older people are among those particularly susceptible to its effects.In response to the deteriorating conditions, authorities have activated Stage II of the Graded Response Action Plan (GRAP), which sets out pollution-control measures to be implemented as air quality worsens.

The measures target several sources of pollution, including road dust and vehicle emissions. They include more frequent road cleaning, higher parking fees to discourage private vehicle use and an expansion of public transport services.

Delhi Metro has added 20 weekday train trips, while government offices have also been directed to stagger working hours to help reduce traffic congestion.

Officials said the measures were introduced following forecasts indicating that air quality would remain in the 'very poor' category over the coming days.

Delhi and surrounding areas in northern India typically experience a deterioration in air quality during winter, BCC noted. The situation often is often expected to become more acute around Diwali, when fireworks add to the concentration of fine particles and harmful gases in the atmosphere.

Beyond firecracker emissions, the region's pollution levels are influenced by several factors, including vehicle exhaust, industrial activity, falling temperatures, slower wind speeds, and the seasonal burning of crop residue in neighbouring states.

Weather conditions and crop burning add to pollution levels

The latest deterioration comes after Delhi recorded its lowest average AQI for October in eight years, an improvement that has since given way to rising pollution levels. Experts have pointed to a combination of lower temperatures, weak winds and increased crop-residue burning in Punjab and Haryana as contributing factors.

Earlier rainfall and stronger winds brought by a storm had helped disperse pollutants. However, as weather conditions changed, northwesterly winds returned, carrying smoke from agricultural fires towards the capital.

With Diwali approaching, the additional emissions from fireworks have raised concerns about a further deterioration in air quality. Last year, the city experienced heavy haze the morning after Diwali, despite a court directive calling for the use of less-polluting firecrackers.

Supreme Court permits limited use of certified green firecrackers

Restrictions on firecrackers have been introduced in Delhi over several years, including bans on their manufacture, sale, and use. However, enforcement has remained a challenge, BBC reported.

On Monday, India's Supreme Court permitted the manufacture, sale and use of certified green firecrackers in Delhi and neighbouring areas for a limited period during the Diwali celebrations.

Under the court's directions, fireworks may be set off only between 06:00 and 07:00 local time (08:30 and 09:30 SGT), and between 20:00 and 22:00 (22:30 and 00:30 SGT) on 7 and 8 November.

The court has also prohibited fireworks within 300 metres of hospitals, care homes, schools and other designated silence zones.

Green firecrackers use modified chemical formulations intended to generate fewer emissions than conventional alternatives. They must also carry QR codes to enable consumers and authorities to verify information about their manufacturers and certification.

However, the availability of unauthorised products remains a concern. In its latest order, the Supreme Court acknowledged that conventional firecrackers had continued to be marketed as green alternatives, even during periods when a complete ban was in effect.

To strengthen enforcement, police have been directed to patrol designated sales areas, conduct random QR-code checks and confiscate illegal firecrackers.

During more severe pollution episodes, authorities have also turned to wider interventions, including hybrid schooling arrangements, work-from-home measures, and restrictions on certain vehicles.

Pollution concerns extend beyond Delhi

The air pollution problem extends beyond India's capital, with several cities across northern India also recording hazardous air quality levels.

According to AQI.in's live ranking on 6 November, Meerut in Uttar Pradesh topped the list with a US AQI reading of 1,014, followed by Hapur in the same state at 890, and Hisar in Haryana at 875.

Other cities among the 10 most polluted included Bathinda in Punjab (852), Rohtak in Haryana (831), and Greater Noida in Uttar Pradesh (744). All 10 cities on the list were classified as having 'hazardous' air quality.

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