Delhi air quality witnesses relief from pollution after rain, strong wind

The residents of Delhi-National Capital Region saw some relief from the alarming air pollution levels following rains and strong winds. The Air Quality Index has been in the ‘severe’ and ‘severe+’ category for over a week. 

Down To Earth (DTE) spoke to experts about the improvement in air quality. At 11 pm on November 9, the AQI in Delhi was recorded as 460, according to System of Air Quality and Weather Forecasting and Research (SAFAR) under the Union Ministry of Earth Sciences. At 9 am  on November 10, it had reduced to 376, in ‘very poor’ category.

According to the AQI scale, a level of 1-50 is ‘good’, 51-100 is ‘satisfactory’, 101-200 is ‘moderate’, 201-300 is ‘poor’, 301-400 is ‘very poor’ and 401-500 is ‘severe’ category. An air quality of more than 501 is in an ‘emergency’ zone.

Read more: Green crackers answer to Diwali pollution but manufacturing limited

“Western disturbances will cause heavy spell of rain over Jammu and Kashmir and Himachal Pradesh on November 10. From November 11, we expect the weather to be clear (experiencing clear skies). As per our forecast, the temperatures will dip from November 11 onwards,” Naresh Kumar, India Meteorological Department (IMD) spokesperson told DTE on November 10.

Specific to a sudden shift in the AQI situation in Delhi and other parts, former IMD chief DS Pai said with rains, there is supposed to be some relief and AQI will reduce. 

“On November 10, by now, the AQI (here) must have  significantly improved, since it rained only yesterday night. These rains are directly  associated with western disturbances. Maybe, we were expecting only light rains but we in fact experienced heavy rains. Once we are (past) through the western disturbances, say after 2-3 days, the situations (in regard to AQI and temperature) might once again change,” he told DTE.   

Read more: Expect Delhi to become a gas chamber again this Diwali

An assessment carried by Delhi-based think tank Centre for Science and Environment (CSE) shows that Delhi’s fine particulate matter PM2.5 levels climbed above 250 micrograms per cubic metre (severe threshold) on November 2 and remained severe for eight days running. This, it states, making the pre-Diwali period one of the long smog episodes in recent years.

“The rains today have given minor relief as levels have come down to the ‘very poor’ category. But we should not get complacent by this temporary short-term relief as the weather forecast for the next few days is not favourable for retaining today’s gains and the probability of PM2.5 levels rising back to severe category is very high,” said Avikal Somvanshi, Urban Lab, CSE, who was behind the analysis.

“Taking further into consideration that SAFAR has forecasted the smoke from the stubble fires will peak on Sunday (this Diwali day), we are staring at a very bad Monday (the day after Diwali),” said Somvanshi. 

Delhi government was also considering measures like artificial rain through cloud seeding to tackle the pollution situation. However, the respite from the measure would have been temporary too. DTE’s reporting in the last 10 days witnessed a severe increase in cases of respiratory diseases and even disclosures of child deaths due to that from doctors across Delhi hospitals. 

Source: CSE analysis of CPCB realtime data

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