Delhi becomes most polluted city in world amid Diwali celebrations

New Delhi regained the dubious distinction of being the most polluted city in the world on Monday night with “hazardous” air quality levels, after an evening of Diwali celebrations involving the bursting of fireworks.

Celebrations with fireworks continued despite a strict ban on their use in the Indian capital, rules that have been flouted by many citizens each year since they were introduced to try and tackle the plummeting air quality in the city every winter.

Swiss organisation IQAir showed Delhi as the most polluted city across the globe on Monday in the “very unhealthy category”, followed by Pakistan’s Lahore.

The concentration of PM2.5 – fine particles in the air that directly impact lungs and can cause permanent respiratory problems – in Delhi is currently 31.5 times the WHO annual air quality guideline value, IQAir’s website read.

Air in Delhi was “hazardous” at 11.30pm on Monday at 446 Air Quality Index (AQI) value, it added. This was the peak time for the bursting of firecrackers, even after police had seized several thousand kilos of fireworks in the days leading up to the festival.

Many smugglers still resorted to the sale of notorious pollution-causing firecrackers out of car boots, inside dusty warehouses and at the back of grocery shops.

Monday’s AQI was the first time Delhi dipped into the “very poor” category since February, barring an anomaly of a few days in July during a freak dust storm.

The air crisis in Delhi, despite being expected to further worsen this week after Diwali, was still a relative improvement on previous years, as the 24-hour average AQI was recorded at 312 by the federal pollution control body.

This is statistically the lowest in four years for Diwali night and the second-best the city has seen in seven years.

Air pollution in northern India and Delhi spikes to its highest during the winter season in October and November every year and is the result of a range of factors including vehicular emissions, industrial smoke, farm fires in neighbouring states and cold, settled meteorological conditions which do not allow the polluted air to disperse.

Delhi also faces severe dust pollution from construction projects in the city and biomass burning, which compound its pollution woes this season.

Meteorological officials monitoring weather conditions in New Delhi had predicted air quality to slip to the “very poor” category last week after days of “poor” AQI.

On Tuesday morning, Delhi and its adjoining regions recorded AQI over 300, landing in the “very poor” category. Prolonged exposure to AQI between 301 and 400 can cause respiratory illnesses and impact children and senior citizens, according to India’s Central Pollution Control Board.

Air quality in New Delhi is likely to remain in the “very poor” to “poor” category for the next few days, according to the Air Quality Early Warning System for the city with average wind speed expected to be unfavourable for carrying away the pollutants.

This could also be impacted by farm fires of residual crops that are expected to surge in northern India, of which more than 2,000 were recorded last week. Farmers in the agriculturally dominant states of Punjab and Haryana burn rice straws to clear up land for the next batch of crops, despite government attempts to introduce fines for the practice.