Day After Diwali, Grey Haze Darkens Delhi Skies

New Delhi: A thick grey haze swallowed the skyline, reduced visibility on roads and brought back irritation in the eyes and throat as Delhi woke up to alarmingly high pollution levels on Monday, after firecrackers were burst across the city well past the permitted hours on Diwali.

The capital’s Air Quality Index (AQI) stood in the ‘very poor’ category at 370 and is expected to deteriorate further to enter the ‘severe’ category during the day.

DTU and Burari Crossing monitoring stations recorded the worst air quality, with an AQI of 437 each. Four other stations recorded ‘poor’ air quality, while the remaining stations were in the ‘very poor’ category.

According to the Central Pollution Control Board (CPCB), an AQI between 0 and 50 is classified as ‘good’, 51 and 100 as ‘satisfactory’, 101 and 200 as ‘moderate’, 201 and 300 as ‘poor’, 301 and 400 as ‘very poor’, and 401 and 500 as ‘severe’.

The air quality remained ‘severe’ in several areas, including Bawana, Burari, Jahangirpuri, Sonia Vihar, Punjabi Bagh, Okhla and Rohini.

According to open-source air quality monitoring platform AQI.in, Delhi’s AQI went up to 2,283 after Diwali. On Monday morning, the AQI stood at 637, which the platform classified as “hazardous”.

Data from Swiss air quality monitoring platform IQAir showed that the concentration of PM2.5 in Delhi stood at 170 micrograms per cubic metre (µg/m³), around 34 times the World Health Organisation‘s (WHO) annual guideline value.

PM2.5, fine particulate matter capable of penetrating deep into the lungs and entering the bloodstream, is among the major pollutants of concern due to its adverse health effects.

The concentration of PM10 was recorded at 126 µg/m³. Ozone levels stood at 31, nitrogen dioxide at 44.6, sulphur dioxide at 32 and carbon monoxide at 1,461.5 µg/m³, IQAir’s data showed.

The Air Quality Early Warning System has forecast that Delhi’s air quality is likely to slip into the ‘severe’ category during the day and will remain there over the subsequent few days.

Unfavourable meteorological conditions, vehicular emissions and stubble burning in neighbouring states are likely to contribute to the deterioration.

A ventilation index below 6,000 square metres per second, coupled with an average wind speed of less than 10 kmph, is unfavourable for the effective dispersion of pollutants, according to the Air Quality Early Warning System.

On Diwali night, firecrackers were burst across the capital, despite restrictions on their use. Twenty monitoring stations recorded ‘severe’ air quality, with Sonia Vihar registering the worst AQI at 463, followed by Jahangirpuri at 450.

The city’s average AQI settled at 376 on Sunday. Of the 59 monitoring stations that recorded data at 10 pm on Diwali, 20 were in the ‘severe’ category, six in the ‘poor’ category and the remaining 33 in the ‘very poor’ category.

Firecracker bursting picked up from around 5-6 pm on Sunday, including in Pitampura, Burari, Mayur Vihar and parts of Lutyens’ Delhi. As celebrations gathered pace through the evening, smoke accumulated over roads and residential neighbourhoods.

Residents in several areas reported a strong smell of burnt crackers, reduced visibility and difficulty breathing as fireworks continued through the night.

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