Delhi woke up on Monday with hazy skies as a blanket of smog engulfed the city after residents widely flouted a firecracker ban on the occasion of Diwali on Sunday. At 11 am on Monday, the air quality index, or AQI, was in the “very poor” category at 23 out of the 35 observation stations in the city for which data was available on the Central Pollution Control Board portal. In areas that come under 11 more stations, the AQI was “poor”.

An air quality index between zero and 50 is considered “good”, 51 and 100 “satisfactory”, 101 and 200 “moderate”, 201 and 300 “poor”, 301 and 400 “very poor” and 401 and 500 “severe”. An AQI in the “very poor” category can lead to respiratory illness on prolonged exposure.

The striking aspect is that on Sunday morning, news reports said that the AQI on Diwali in the capital city was the best in eight years due to rainfall on Friday. However, the air quality worsened sharply on the evening of Diwali,correlated with the mass use of firecrackers for the festival.


Firecracker effect

Despite the air quality visibly deteriorating on Monday morning, Bharatiya Janata Party social media cell chief Amit Malviya claimed that owing it to firecrackers was an attempt to “malign Hindus”.

Malviya’s claim is an argument put forward by supporters of firecrackers every year after Diwali even as experts have argued otherwise.

In a forecast issued on Saturday, the System of Air Quality and Weather Forecasting and Research, which operates under the Union Ministry of Earth Sciences, had predicted that the air quality in Delhi would worsen considerably if firecrackers were to be used on Diwali.

The Pune-based research centre predicted that the “poor” air quality of Delhi on Saturday would worsen to “very poor” if there were zero firecracker emissions. However, in the case of firecracker emissions being present, AQI would shoot up by 50%, SAFAR had said.

Photo: System of Air Quality and Weather Forecasting and Research

As things stood on Monday morning, the air quality was much worse than even what SAFAR had predicted. The air quality being “very poor” in the majority of observation stations in Delhi indicated that AQI was above 300 in most parts of Delhi, as against 218 predicted by SAFAR in their worst case scenario.

Also read: Why is the Supreme Court’s regulation of firecrackers so ineffective in curbing air pollution?

A case in point is the observation station at the Indian Agricultural Research Institute, known as PUSA Institute in Delhi. This station is one of the six in Delhi operated by the India Meterological Department.

At 11 am on Sunday, the AQI at the PUSA Institute was 117 – in the “moderate” category. On Monday morning, the AQI was “very poor” at 383.

The trend of air quality worsening in Delhi a day after Diwali has in fact been consistent over the years.