Delhi’s annual air quality index worsens, to further deteriorate next week

Delhi’s air quality index (AQI) reading, jumped from 127 on Thursday to 167 on Friday, and then to 171 on Saturday

With the withdrawal of monsoon from Delhi — and other parts of northwest India — on Friday, the Capital’s recent run of clear, clean, cerulean skies has started to give way to an annual veil of smog borne largely by stubble fires in neighbouring states. Data from the central pollution watchdog shows that the city’s air quality has seen a gradual, but sustained, drop over the past 10 days. And as farm fires pick up in Haryana and Punjab, Delhi’s air is only likely to get worse over the coming week.

As farm fires pick up in Haryana and Punjab, Delhi’s air is only likely to get worse over the coming week. (Sakib Ali/HT Photo)

The India Meteorological Department (IMD) on Friday declared the withdrawal of the south-west monsoon from Delhi, which means that the moisture-laden easterly winds blowing over the Capital have now been replaced with dry, north-westerly winds. These winds will bring down temperatures, but push pollution levels, said weather forecasters.

Recordings by the Central Pollution Control Board (CPCB) show that as the wind patterns changed on Friday, air quality levels fell sharply.

Delhi’s air quality index (AQI) reading, jumped from 127 on Thursday to 167 on Friday, and then to 171 on Saturday.

An AQI 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’.

Experts said that this is the impact of stubble fires in the neighbouring agrarian states of Punjab and Haryana.

Scientists from the United States’s National Aeronautics and Space Administration (NASA) said that the rise in farm stubble burning is visible in the increased number of “fire dots” spotted over the region on satellite imagery.

“Over the last one week, as the clouds have cleared up, there is a consistent increase in the number of fires appearing over north India. This will start impacting the region’s air quality,” said Pawan Gupta, a research scientist at the Goddard Earth Sciences Technology and Research (GESTAR), Universities Space Research Association.

NASA’s fire map on Saturday showed a jump in fires over parts of Amritsar, Gurdaspur, Tarn Taran, Ludhiana, Shahid Bhagat Singh Nagar and Sangrur in Punjab. In Haryana, fires were observed in parts of Kaithal, Kurukshetra, Ambala, Yamuna Nagar, Karnal and Panipat.

Delhi chief minister Arvind Kejriwal also warned Delhiites of the impending deterioration of the city’s air quality in a series of tweets on Friday and Saturday.

Kejriwal has tweeted out the city’s daily air quality for the past month to establish that the AQI in the city, with only local pollution sources at play is in the “acceptable” range, but as soon as farmers in the neighbouring states start setting their fields on fire, the air quality in Delhi starts taking a nosedive.

“Pollution has started increasing. 09 Oct-AQI – 171...,” Kejriwal tweeted on Saturday.

Weather forecasters warned that from October 15, temperatures will start falling, which will increase the share of stubble smoke in the city’s air.

“At present, Delhi is largely getting north-westerly winds with some components of westerly winds, but there is a forecast of day and night temperatures falling from October 15, which will lead to the formation of haze because of the stubble fire smoke. The air quality is likely to get bad from here on,” said Mahesh Palawat, vice-president (meteorology and climate change) at Skymet Weather Services.

Union Ministry of Earth Science’s air quality monitoring system, System of Air Quality and Weather Forecasting and Research (Safar), also forecasted the impending worsening of air quality in Delhi. They also highlighted that the primary pollutants in the city’s air on Friday were “fire emissions and dust suspensions”.